Fixes #377. Split Ocean Grid Comp into new repo

[mathomp4]

Okay. GEOS_OceanGridComp was split into a new repo following:

mkdir MakeNewOceanGridComp
cd MakeNewOceanGridComp
git clone git@github.com:GEOS-ESM/GEOSgcm_GridComp.git
cd GEOSgcm_GridComp/
git filter-repo --subdirectory-filter GEOSogcm_GridComp/GEOS_OceanGridComp
git reset --hard
git gc --aggressive
git prune
git clean -fd
git remote add origin git@github.com:GEOS-ESM/GEOS_OceanGridComp.git
git branch -M main
git push -u origin main

I'm still testing this, but so far so good. Will of course require a PR to GEOSgcm_GridComp and new tag.

Depends on: GEOS-ESM/GEOSgcm_GridComp#551

[mathomp4]

My tests show that the split-off ocean is zero-diff.