Add Inertial gravity wave test group

[sbrus89]

This PR adds a convergence study for the inertial gravity wave from Sid's paper

Note that this case relies on the linearization options added to MPAS-Ocean by @mark-petersen in https://github.com/E3SM-Project/E3SM/pull/5662.

Checklist

• [x] User's Guide has been updated
• [x] Developer's Guide has been updated
• [x] API documentation in the Developer's Guide (api.md) has any new or modified class, method and/or functions listed
• [x] Documentation has been built locally and changes look as expected
• [x] Testing comment in the PR documents testing used to verify the changes
• [x] New tests have been added to a test suite

[sbrus89]

Testing:

The convergence test case runs a 200, 100, 50, and 25 km case for 10 hours and compares the errors against the exact solution:

[cbegeman]

@sbrus89 I'll review this tomorrow

[sbrus89]

@cbegeman, thanks for testing again. I'm testing one more time on Perlmutter just to make sure everything works with the latest changes in https://github.com/E3SM-Project/E3SM/pull/5662. I realized we should probably wait for the linearization option merge in E3SM. Then we can update the submodule as a part of this PR.

[cbegeman]

@xylar Would you like to re-review this PR or is it ready for me to merge? The E3SM PR is in now.

[sbrus89]

Thanks @xylar and @cbegeman!