Generify OpenVR module into a VR module and rework OpenVR module accordingly

Master issue for future VR developments #18302 (closed)

MR to adapt the Paraview OpenVR plugin (and rename it to VRPlugin) to work with theses new changes

MR for the functional Generic VR branch

This branch creates a new "VR" module to factorize code between OpenVR module (and future OpenXR module, not in this MR).

For instance, only the simplest factorization has been done to be merged quickly :

• Unchanged classes :
  • the vtkOpenGLAvatar and its data (in the data/ folder)
  • CollaborationHelper
  • Follower
  • HardwarePicker
  • Menu Representation + Widget
  • Panel Representation + Wiget
  • Ray
• Classes that need to be overriden by specific API classes (OpenVR or OpenXR for example) :
  • the Camera that act only as a shell to hold the GetTrackingToDCMatrix (used in vtkVRModel)
  • the ControlsHelper to InitControlPosition at the controller's button position
  • The VRModel to :
    • Create and setup the VBO+IBO from the controller mesh
    • Create and load the texture object and model
  • The RenderWindow to :
    • Create the framebuffers
    • Get the PoseMatrixWorld from an EventDataDevice
    • Specify how to destroy specific API resources (ReleaseGraphicResources)
    • Specify the size of the HMD
    • Specify the name of the window
    • Initialize and finalize the window (API initialization+shutdown, etc..)
  • The Renderer to create a specialized Camera in MakeCamera()

The InteractorStyle and RenderWindowInteractor are not handled here, as well as the overlay