[wpimath] Mark all geometry classes as final (#8790)

In Java, these are likely to become value classes in the future.

Make C++ final for consistency.

wpimath/src/main/native/include/wpi/math/geometry/Pose2d.hpp

@@ -27,7 +27,7 @@ class Transform2d;
 /**
  * Represents a 2D pose containing translational and rotational elements.
  */
-class WPILIB_DLLEXPORT Pose2d {
+class WPILIB_DLLEXPORT Pose2d final {
  public:
   /**
    * Constructs a pose at the origin facing toward the positive X axis.