Fix OpenVR initialization (fixes crash on VTK >= 9.1)

Since VTK 9.1 (tested with releases only), the vtkOpenVRRenderWindow needs to be explicitly initialized, otherwise the program crashes. This adds the initialization for all OpenVR examples.

Fixes vtk#18433 (closed)

src/Cxx/GeometricObjects/OpenVRCone.cxx

@@ -32,6 +32,7 @@ int main(int, char*[])
       vtkSmartPointer<vtkOpenVRRenderer>::New();
   vtkSmartPointer<vtkOpenVRRenderWindow> renderWindow =
       vtkSmartPointer<vtkOpenVRRenderWindow>::New();
+  renderWindow->Initialize();
   renderWindow->AddRenderer(renderer);
   vtkSmartPointer<vtkOpenVRRenderWindowInteractor> renderWindowInteractor =
       vtkSmartPointer<vtkOpenVRRenderWindowInteractor>::New();