Update building mapping files with moab

[xylar]

This merge reorganizes support for generating mapping files using MOAB's mbtempest and related tools. This work relates to changes made by @bmooremaley in MPAS-Dev/compass#863.

Checklist

• Testing comment in the PR documents testing used to verify the changes

[xylar]

I'm able to create a mapping file (very quickly) with this approach but I'm having trouble remapping 2D data with it because the 2 dimensions have been flattened into 1 in the mapping file. The solution may be to flatten the 2D data before remapping.

[xylar]

The fix for the mapping problem above is:
https://bitbucket.org/fathomteam/moab/branch/vijaysm/propagate-rll-dims

[xylar]

Thanks to @vijaysm for the help!

[xylar]

I will get back to this in the coming week.

[xylar]

Testing

I successfully ran the following tests on Chrysalis:

ocean/planar/isomip_plus/4km/z-star/ocean0
ocean/planar/isomip_plus/1km/z-star/ocean0

I also looked at the resulting topography_remapped.nc on the culled mesh in ParaView and things looked as expected.

Since ISOMIP+ is the only set of tests that currently uses this remapping functionality, I think that is sufficient testing for now.

[xylar]

@bmooremaley, I know you're not really funded to work on Polaris or MOAB or anything related to this PR at the moment. I'm wondering if you'd take a quick look at the code even so and let me know if anything jumps out at you. If not, please approve so I can merge it.

[xylar]

I'd like to move ahead with #151 (on hold for too long), which requires this work. So I'm going to go ahead and merge this.