Enable OpenVR for iMSTK on Windows
Able to launch any example in VR
Switch parameter (VTKViewer::m_openVR) added toggling between desktop/VR app. For instance, to enable VR, you just have to call from your main: SimulationManager::getViewer()::setVRMode(true)
VTK GIT_TAG in order to have mainly the following features/fixes:
- vtk/vtk!2549 (merged)
- vtk/vtk!2574 (merged)
- Merge Request needed to launch MiddleButtonRelease/PressEvent() on vr::EVRButtonId::k_EButton_Grip in vtkOpenVRRenderWindowInteractor::DoOneEvent() --> [DONE]: vtk/vtk!2609 (merged)
ssh issue fixed by https ( should maybe moved in a separate MR)

Infrastructure

imstkVTKViewer initializes RenderWindow, Interactor and callbacks (InteractorStyle for NONopenVR / vtkCommand for OpenVR)
imstkOpenVRCommand is a subclass of vtkCommand which defines the callbacks on VR button
imstkVTKRenderer instantiates the Renderer and the Camera

Add Command for Vive Remote

Trigger Button to switch run/pause simulation
Home button to switch start/end simulation
Use vtkCommand::StartEvent to do a VTKRenderer::updateRenderDelegates() instead of overriding OpenVRRenderWindowInteractor::DoOneEvent()
Grip Button to take a screen shot (Innerbuild/Examples/Sandbox/screenShot_X.png)

openVRCamera: ActiveCamera in VR will always have to be the m_defaultVtkCamera. The m_sceneVtkCamera is used to load its world coordinate position
Switching to simulation mode move you to the m_sceneVtkCamera camera position
Switching to debug mode (when simulation ended for example) move you to your previous debug mode position statement

Fix the CMake part to download the right VTK Version
CMake part to fill various option when openVR enabled (it shouldn't make the build crash) + Doc
Copy OpenVRDashboard.jpg from External/VTK/ to iMSTK-build/bin (same place where we run the .exe)
Move m_openVR outside VTKViewer constructor
Trigger command bugs (start/stop simulation when translation/scaling multi-touch or during dashboard interactions) --> need to disable scaling in simulation mode
In dashboard mode: do not allow to interact with the simulation (+ stop simulation if it was running)
Move camera to debug/sim camera when toggling mode