Add FRIS comparison grid

[irenavankova]

Adds the option to make plots on a grid that focuses on the Filchner-Ronne cavity.

Here is an example bsf plot with that option:

[xylar]

This looks good! I'll give it a couple of quick tests tomorrow and then merge if things work as expected.

[xylar]

Regarding documentation, https://github.com/MPAS-Dev/MPAS-Analysis/blob/develop/docs/users_guide/config/comparison_grids.rst is so woefully out of date that it doesn't make sense to try to fix it here.

[xylar]

I ran the test suite and things look good:
https://web.lcrc.anl.gov/public/e3sm/diagnostic_output/ac.xasay-davis/analysis_testing/chrysalis/add_fris_comparison_grids/

I pushed a commit that adds the Fris comparison grid to the test suite. @irenavankova, I hope that's fine with you.