Catalyst: support pvsm state files as pipelines
With support for extract generators, a ParaView state includes relevant information for generation of extracts in situ. Typically, the current workflow is save out Python state file and load that in situ. We should support non-python state files (i.e. pvsm) as well. This will make it possible for simulations to not depend on Python -- which has been a pain point for some HPC use-cases.