Follow-up from "Add rendering ui"

The following discussion from !6470 (merged) should be addressed:

• @michael.migliore started a discussion: (+1 comment)

  @ken-martin when configured the first time on linux, VTK_USE_X is not set yet and the factory do not create vtkXRenderWindowInteractor but vtkGenericRenderWindowInteractor.
  Two workarounds are possible:

  • Configuring VTK a second time fix the issue because VTK_USE_X is now set.
  • Use -DVTK_USE_X=ON explicitly when configuring VTK.

  The issue is similar on OSX with VTK_USE_COCOA.
  Imo, this should be fixed before 9.0 release.
  Quick fix: adding VTK::opengl in RenderingUI module dependencies where VTK_USE_X is defined but I'm not sure this is what we want.

  cc @mwestphal