DOCN_SOM_FILENAME

There was previously (in the MCT data models) the capability for the user to set DOCN_SOM_FILENAME for the SOM forcing file in env_run.xml. This has gone away in CDEPS. I would like at a minimum for this to be added back. The default for this currently is the 1x1d forcing file: $DIN_LOC_ROOT/ocn/docn7/SOM/pop_frc.1x1d.090130.nc in cime_config/stream_definition_docn.xml.

Also, I had this previously so that there was no default and make the user set it. So, DOCN_SOM_FILENAME would be UNSET. However, for testing purposes we had an ETEST and DTEST compset where it would just use the default filename above. I wonder if this behaviour was no longer desired and the preference was to always have a default? Happy to discuss this further.