Add `vtkDelayedSphereSource`
requested to merge christos.tsolakis/paraview:introduce-filter-wtih-custom-delay-for-testing into master
A filter similar to vtkSphereSource but with a configurable
time delay to simulate long-running filters.
@utkarsh.ayachit : I am not a big fan of the name but I am not sure what is more appropriate. Let me know what you think.