[Paraview] created representation is invisible in view

[Utkarsh Ayachit]

You're missing "adding the representation to the view" part, typically
done using vtkSMParaViewPipelineControllerWithRendering::Show.

See this example:

https://gitlab.kitware.com/paraview/paraview/blob/master/ParaViewCore/ServerManager/Rendering/Testing/Cxx/TestParaViewPipelineControllerWithRendering.cxx#L126-128