Partitioned dataset collection improvements
Miscellaneous improvements to support data assemblies in ParaView.
Among the bigger changes,
vtkSelectionNode now supports qualifying selections using data assemblies.
Another change is pending after this MR is merged. We need to change the hierarchy to match the naming convention discussed here, however I don't want to that right now as I am sure that will require another pass of updating tests etc. I'll do that in a new MR once the dust settles from this (and matching ParaView MR).
Also fixes #18128 (closed)