Cleanup: split 'transform_gizmo_3d.cc' in more specific units

Split `transform_gizmo_3d.cc` in:
- `transform_gizmo_3d.cc`
- `transform_gizmo_3d_cage.cc`
- `transform_gizmo_3d_shear.cc`

Split `transform.h` in:
- `transform.h`
- `transform_gizmo.h`

Also:
- Move functions `gimbal_axis_pose` and `gimbal_axis_object` to
`transform_orentations.c` (they are not used in `transform_gizmo_3d.cc`)

Pull Request #105256

source/blender/editors/transform/transform_constraints.c

@@ -34,6 +34,7 @@
 #include "UI_resources.h"
 
 #include "transform.h"
+#include "transform_gizmo.h"
 #include "transform_orientations.h"
 #include "transform_snap.h"