SYSTEM AND METHOD FOR DETECTING A POSITION OF A CUTTER BLADE FOR A CASING CUTTER CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Application No.17/398212, filed on August 10, 2021, which is incorporated herein by reference in its entirety. BACKGROUND [0002] In the resource recovery industry, casings are provided in a wellbore to support wellbore surfaces. The casing may also support downhole systems such as hangers, support packers, and the like. At some point during a life of the wellbore it may be desirable to remove the casing. Typically, the casing is removed in sections. That is, a casing cutter is lowered into the wellbore and manipulated to cut through the casing at selected intervals forming casing sections. The casing sections may then be removed from the wellbore. [0003] The casing cutter includes a plurality of knives that rotate outward as pressure is applied to a piston. As the knives penetrate the casing, to position of the cutter blade changes. As the position of the cutter blade changes, the cut deepens until a full cut is achieved. The industry would welcome a system for providing definitive feedback concerning cutter blade position and angle relative to the casing in order to better understand when a cut is complete. SUMMARY [0004] Disclosed is a casing cutting system including a tubular having a first end, a second end, an inner surface defining a passage extending between the first end and the second end, an outer surface, and a window extending through the inner surface and the outer surface. A deployment member is mounted in the passage. A plurality of cutter blades is arranged in the passage at the window. The plurality of cutter blades is pivotally mounted to the deployment member. A sensor is operatively coupled to the deployment member. The sensor is operable sense an amount of travel of each of the plurality of cutters. [0005] Also disclosed is a resource exploration and recovery system including a surface system, a subsurface system including a casing tubular, and a tubular string extending from the first system into the casing tubular. The tubular string includes a casing cutting system including a tubular having a first end, a second end, an inner surface defining a passage extending between the first end and the second end, an outer surface, and a window extending through the inner surface and the outer surface. A deployment member is mounted in the passage. A plurality of cutter blades is arranged in the passage at the window. The plurality of cutter blades is pivotally mounted to the deployment member. A sensor is operatively coupled to the deployment member. The sensor is operable sense an amount of travel of each of the plurality of cutters. [0006] Further disclosed is a method of determining cutter blade position in a casing cutter system including positioning the casing cutter system at a select location along a casing tubular, providing an activation stimulus to a deployment member, rotating a plurality of cutter blades outwardly into contact with the casing tubular, and measuring an amount of rotation of the plurality of cutter blades. BRIEF DESCRIPTION OF THE DRAWINGS [0007] The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike: [0008] FIG.1 depicts a resource exploration and recovery system including a casing cutter having a blade position sensing system, in accordance with a non-limiting example; [0009] FIG.2 depicts a cross-sectional side view of the casing cutter of FIG.1 with the cutter blades in a first position; [0010] FIG.3 depicts a cross-sectional side view of the casing cutter of FIG.1 with the cutter blades in a second position; and [0011] FIG.4 depicts a block diagram illustrating a control system for managing operation of the casing cutter, in accordance with a non-limiting example. DETAILED DESCRIPTION [0012] A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures. [0013] A resource exploration and recovery system, in accordance with an exemplary embodiment, is indicated generally at 10, in FIG.1. Resource exploration and recovery system 10 should be understood to support well drilling operations, completions, resource extraction and recovery, CO ₂ sequestration, and/or the like. Resource exploration and recovery system 10 may include a first system 14 which, in some environments, may take the form of a surface system 16 operatively and fluidically connected to a second system 18 which, in some environments, may take the form of a subsurface or downhole system (not separately labeled). [0014] First system 14 may include a control system 23 that may provide power to, monitor, communicate with, and/or activate one or more downhole operations as will be discussed herein. Surface system 16 may include additional systems such as pumps, fluid storage systems, cranes, and the like (not shown). Second system 18 may include a casing tubular 30 that extends into a wellbore 34 formed in a formation 36. [0015] Casing tubular 30 may be part of a completion and could be formed from a plurality of interconnected tubulars (not separately labeled). Wellbore 34 includes an annular wall 40 which may be defined by a surface of formation 36. Casing tubular 30 includes an inner surface 44 and an outer surface 46. A tubular sting 48 extends from first system 14 into formation 36 through casing tubular 30. Tubular sting 48 supports a casing cutting system 50 that is selectively activated to create one or more annular cuts in casing tubular 30. The annular cuts separate casing tubular 30 into two or more sections to facilitate removal. [0016] Referring to FIG.2, casing cutting system 50 includes a tubular 58 having a first end 60 and an opposing second end 62. Tubular 58 also includes an outer surface 64 and an inner surface 66 defining a passage 68 that extends axially between first end 60 and second end 62. Tubular 58 includes a window 70 that extends through outer surface 64 and inner surface 66. A deployment member 72 is slidingly mounted in passage 68 spaced from window 70. Deployment member 72 includes a seal portion 74 that engages inner surface 66, an actuator portion 77, and a spring 80 that extends about actuator portion 77 and biases deployment member 72 towards first end 60. [0017] Tubular 58 also supports a plurality of cutter blades, one of which is indicated at 84, that selectively pass through window 70 and engage inner surface 44 of casing tubular 30. Cutter blades 84 are urged outwardly to cut through casing tubular 30. Each cutter blade 84 includes a pivot 86 and an actuator 88. Cutter blades 84 rotate about pivot 86 when deployment member 72 acts on actuators 88. A carrier element 96 is arranged in passage 68 and is fixed relative to inner surface 66. Carrier element 96 is spaced from deployment member 72 by an activation volume 100. A plurality of passages 102 extend through a support element 104 to fluidically connect activation volume 100 with a source of fluid (not shown). [0018] In accordance with a non-limiting example, casing cutting system 50 includes a sensor 116 that can detect and transmit to surface system 16 an amount of movement of cutter blades 84. Sensor 116 includes a first sensing element 120 mounted to deployment member 72 and a second sensor 124 mounted to carrier element 96. First sensor element 120 may take the form of a magnet 130, such as a ring magnet, disposed in passage portion (not separately labeled) formed in deployment member 72. Second sensor element 124 takes the form of a metallic element 134 such as a rod 136 which passes through the ring magnet 130 into the passage portion. Relative movement between magnet 130 and rod 136 as shown in FIG.3 can be measured. That is, sensor 116 may take the form of an inductive displacement sensor in accordance with a non-limiting example. At this point, it should be understood that the relative positions of first sensor element 120 and second sensor element 124 may be reversed. [0019] Referring to FIG.4, sensor 116 is connected to control system 23. Fluid is introduced into activation volume 100 via carrier element 96. Deployment member 72 acts on actuators 88 causing cutter blades 84 to rotate outwardly. Casing cutting system 50 rotates and cutter blades 84 engage and bite into inner surface 44. Pressure is increased in activation volume 100 forcing deployment member 72 further into contact with actuators 88 driving cutter blades 84 deeper into casing tubular 30. As deployment member 72 moves, magnet 130 transitions over rod 136. Changes in induction due to that movement is passed to control system 23 which in turn calculates a depth of cut. [0020] Control system 23 includes a CPU 144 and a non-volatile memory 146. Memory 146 includes a set of instructions which guide CPU 144 to translate the liner movement of deployment member into a rotational movement of cutter blades 84. Control system 23 outputs to, for example, a display 150 an amount of the rotational movement providing operators with real time updates concerning cutting depth and when a full cut is achieved. Providing operators with additional data creates a deeper understanding regarding the cutting progress and thereby reduces cutting time, protects cutters, and reduces rig time. It should be understood that casing cutting system 50 may be employed to cut a single casing tubular, multiple strings, or layers of casing tubular, and may be repositioned to make multiple cuts in order to formed casing segments in order to facilitate casing removal. [0021] Set forth below are some embodiments of the foregoing disclosure: [0022] Embodiment 1. A casing cutting system comprising: a tubular including a first end, a second end, an inner surface defining a passage extending between the first end and the second end, an outer surface, and a window extending through the inner surface and the outer surface; a deployment member mounted in the passage; a plurality of cutter blades arranged in the passage at the window, the plurality of cutter blades being pivotally mounted to the deployment member; and a sensor operatively coupled to the deployment member, the sensor being operable sense an amount of travel of each of the plurality of cutters. [0023] Embodiment 2. The casing cutting system according to any prior embodiment, wherein the deployment member is shiftable along the passage to rotate the plurality of cutter blades, the sensor detecting a displacement of the deployment member to measure the amount of travel. [0024] Embodiment 3. The casing cutting system according to any prior embodiment, further comprising: a carrier element separated from the deployment member by an activation volume, the carrier element being fixedly mounted in the passage and including one or more openings fluidically connecting the activation volume with a source of fluid. [0025] Embodiment 4. The casing cutting system according to any prior embodiment, wherein the sensor includes a first sensor element mounted to the deployment member and a second sensor element mounted to the carrier element. [0026] Embodiment 5. The casing cutting system according to any prior embodiment, wherein the first sensor element comprises one of a magnet and a metallic element and the second sensor element comprises another of the magnet and the metallic element. [0027] Embodiment 6. The casing cutting system according to any prior embodiment, wherein the first sensor element comprises the magnet and the second sensor element comprises the metallic element. [0028] Embodiment 7. The casing cutting system according to any prior embodiment, wherein the magnet comprises a ring magnet embedded in the deployment member and a metallic rod extending from the carrier member through the ring magnet. [0029] Embodiment 8. A resource exploration and recovery system comprising: a surface system; a subsurface system including a casing tubular; and a tubular string extending from the first system into the casing tubular, the tubular string including a casing cutting system comprising: tubular including a first end, a second end, an inner surface defining a passage extending between the first end and the second end, an outer surface, and a window extending through the inner surface and the outer surface; a deployment member mounted in the passage; a plurality of cutters arranged in the passage at the window, the plurality of cutter blades being pivotally mounted to the deployment member; and a sensor operatively coupled to the deployment member, the sensor being operable sense an amount of travel of each of the plurality of cutters. [0030] Embodiment 9. The resource exploration and recovery system according to any prior embodiment, wherein the deployment member is shiftable along the passage to rotate the plurality of cutter blades, the sensor detecting a displacement of the deployment member to measure the amount of travel. [0031] Embodiment 10. The resource exploration and recovery system according to any prior embodiment, further comprising: a carrier element separated from the deployment member by an activation volume, the carrier element being fixedly mounted in the passage and including one or more openings fluidically connecting the activation volume with a source of fluid. [0032] Embodiment 11. The resource exploration and recovery system according to any prior embodiment, wherein the sensor includes a first sensor element mounted to the deployment member and a second sensor element mounted to the carrier element. [0033] Embodiment 12. The resource exploration and recovery system according to any prior embodiment, wherein the first sensor element comprises one of a magnet and a metallic element and the second sensor element comprises another of the magnet and the metallic element. [0034] Embodiment 13. The resource exploration and recovery system according to any prior embodiment, wherein the first sensor element comprises the magnet and the second sensor element comprises the metallic element. [0035] Embodiment 14. The resource exploration and recovery system according to any prior embodiment, wherein the magnet comprises a ring magnet embedded in the deployment member and a metallic rod extending from the carrier member through the ring magnet. [0036] Embodiment 15. A method of determining cutter blade position in a casing cutter system comprising positioning the casing cutter system at a select location along a casing tubular; providing an activation stimulus to a deployment member; rotating a plurality of cutter blades outwardly into contact with the casing tubular; and measuring an amount of rotation of the plurality of cutter blades. [0037] Embodiment 16. The method according to any prior embodiment, further comprising sending the amount of rotation to a surface system. [0038] Embodiment 17. The method according to any prior embodiment, wherein measuring the amount of rotation includes sensing an axial displacement of the deployment member. [0039] Embodiment 18. The method according to any prior embodiment, wherein sensing the amount of displacement includes detecting an amount of movement of a first sensor element relative to a second sensor element. [0040] Embodiment 19. The method according to any prior embodiment, wherein detecting the amount of movement includes sensing a change in induction. [0041] Embodiment 20. The method according to any prior embodiment, wherein sensing the change in induction includes sensing energy at a metallic element passing through a magnet mounted to the deployment member. [0042] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “about”, “substantially” and “generally” are intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” and/or “substantially” and/or “generally” can include a range of ± 8% or 5%, or 2% of a given value. [0043] The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and / or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc. [0044] While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited.