Request: expose surface_variables_tables as an importable asset for downstream analysis

[jsta]

Would be very useful to downstream analyses if surface_variables_tables.rst was exposed as an importable asset for downstream analyses

Also this is beyond the scope of this repo but having the output (history) variable definitions would also be great:
https://escomp.github.io/CTSM/users_guide/setting-up-and-running-a-case/history_fields_fates.html