Merge branch 'mark-petersen/ocean/update_mpas_coastal' (PR #3015)

Update MPAS-Ocean for coastal applications

This PR brings in a new mpas-source submodule, with changes to
mpas-ocean source code. The various additions are all for MPAS-Ocean coastal
applications, and include:
* Addition of COMPASS test cases for coastal (does not impact E3SM);
* Add implicit Rayleigh drag (default off); and
* Alterations for wetting/drying (default off)
Since all modifications are either off by default or do not impact E3SM,
this PR should not change answers.

[BFB]