Stereo cursor plugin

The Stereo Cursor View is a Render View containing a 3D cursor. The 3D cursor is a widget that is created alongside the view. It is placed in the scene depending on the position of the mouse: if it hovers an actor, the cursor is placed on its surface. If not, the cursor is placed on the focal plane of the camera. For now, the cursor do not work with volumes.

Needs vtk/vtk!9894 (merged)