Updates src/MOM6 and src/SIS2 for use with fms2_io

[thomas-robinson]

This updates ESM4-maintenance to be compatible with fms2_io. It cherry-picks @nikizadehgfdl updates that are needed in mom and sis. This needs to be updated for the EMS4 public model

[marshallward]

I can't find hashes for these versions of MOM6 and SIS2 in our repositories. Are there changes from @nikizadehgfdl that are not yet merged?

If not, would be better to first get them in the main branches, or at least identify a commit in NOAA-GFDL/{MOM6,SIS2} with the required changes?

[thomas-robinson]

These commits are cherry-picked from @nikizadehgfdl 's fork. My understanding is that these are the minimum changes needed for compatibility with fms2_io.
Is there an ESM4-maintenance branch in MOM6 and SIS2 to merge Niki's changes into?

[nikizadehgfdl]

These cherrypicks are NOT needed for dev/gfdl as dev/gfdl already has them in some form.
These are only needed for ESM4-maintanance branch to run with FMS202* and preserving the ESM4.0/CM4.0 CMIP6 answers.
dev/gfdl compiles/runs with FMS202* but it changes ESM4.0/CM4.0 answers (due to a vast number of MOM6 updates between ESM4-maintanance branch and FMS2 support ).

[marshallward]

Thanks @nikizadehgfdl for that explanation. I am not at all familiar with ESM4 or its maintenance branch, but that makes sense to me. @thomas-robinson did you create these MOM6/SIS2 commits via cherry-pick? I cannot find them in Niki's repo either.

It looks like MOM6 and SIS2 have ESM4-maintenance branches, so it's possible these new commits could be added to those branches.

[thomas-robinson]

I submitted PRs to MOM6 and SIS2. Both are on the ESM4-maintenance branch for their repos.