Add RobotPoseEstimator (#571)

RobotPoseEstimator can pick the most likely pose for the robot given a number of possible poses, using a number of different strategies. Examples are still WIP.

photon-lib/src/main/native/include/photonlib/PhotonCamera.h

@@ -67,11 +67,13 @@ class PhotonCamera {
    */
   explicit PhotonCamera(const std::string_view cameraName);
 
+  virtual ~PhotonCamera() = default;
+
   /**
    * Returns the latest pipeline result.
    * @return The latest pipeline result.
    */
-  PhotonPipelineResult GetLatestResult();
+  virtual PhotonPipelineResult GetLatestResult();
 
   /**
    * Toggles driver mode.
@@ -155,6 +157,10 @@ class PhotonCamera {
     PhotonCamera::VERSION_CHECK_ENABLED = enabled;
   }
 
+  // For use in tests
+  bool test = false;
+  PhotonPipelineResult testResult;
+
  protected:
   std::shared_ptr<nt::NetworkTable> mainTable;
   std::shared_ptr<nt::NetworkTable> rootTable;