(STrackballCamera): move the trackball interaction to a new adaptor

What does this MR do?

• Decouples the trackball interactor from the layer.
• Moves trackball interactions to a new service.
• Makes 'fixed' interactions the default.
• Deprecate parts of the SInteractorStyle.

How to test it?

• Run OgreViewer or TutoOgreGenericScene
• Run your own app if it uses Ogre

Associated Issues/Merge Requests

• Issues

  • Fixes #429 (closed)

• Merge requests

  • depends on !317 (merged)