(VRWidgetsInteractor): move the clipping interaction to a separate class

What does this MR do?

• Refactors dvr widget interaction. Splits VRWidgetsInteractor into TrackballInteractor and ClippingBoxInteractor and deprecates it.
• Adds right mouse button interaction to the trackball.
• Renames VRWidget to ClippingBox.

How to test it?

• Run OgreViewer
• Load an image
• Interact with the scene

• Issues
  • Fixes #428 (closed)