(MeshPickerInteractor): new service for mesh picking interactions

What does this MR do?

• Refactors the IInteractor API to handle keyboard modifications.
• Adds a new visuOgreAdaptor::SPicker to handle picking interactions instead of SInteractorStyle

How to test it?

• Run OgreViewer
• Load a mesh
• Pick the mesh using Ctrl+left click.

Associated Issues/Merge Requests

• Issues

  • Fixes #431 (closed)

• Merge requests

  • depends on !319 (merged)