Once silo/overlink extract is added, add ability for silo/overlink options to flow through

[JustinPrivitera]

https://github.com/LLNL/conduit/blob/fa0f8d3738b0c4cef95a0d05003f3b80aa381f23/src/libs/relay/conduit_relay_io_silo.cpp#L5690

Some of these will be covered already - overlink file style, num files. But others would be nice to support: silo_type, root_file_ext, etc.

[JustinPrivitera]

I think, once we get this implemented, we should remove all the MPI logic I have written to check that only a single topology is selected. We can just use the ovl_topo_name argument instead. Conduit will warn users that they are attempting to write multiple with Overlink and it will tell them which choice it made. They can use the argument to control this instead of enforcing it in Ascent.

[JustinPrivitera]

silo/overlink extract will be added in #1377