Translate variable names for Omega before baseline validation

[xylar]

To accomplish this, this PR moves Omega <--> MPAS-Ocean variable translation to the Ocean component class. It removes the unneeded Omega --> MPAS-Ocean dictionaries (we can use the MPAS-Ocean --> Omega dictionaries for both direction). It also adds methods for translating a list of variable names, rather than a dataset (useful for validation variables).

This approach prevents redundant building of the translation maps for each step that needs them and makes the translation available beyond OceanIOSteps.

OceanIOSteps has been updated to use the methods from Ocean component for mapping variable and dimension names.

Checklist

• API documentation in the Developer's Guide (api.md) has any new or modified class, method and/or functions listed
• Documentation has been built locally and changes look as expected
• Testing comment in the PR documents testing used to verify the changes

Fixes #395

[xylar]

Testing

After struggling to test on Perlmutter, I switched to Chrysalis (with Intel), where I was able to successfully run both the omega_pr and MPAS-Ocean pr suites, including baseline comparisons. All tests passed -- baseline comparisons passed as expected (given the baseline and comparison Polaris and ocean components are the same).

[xylar]

@cbegeman, could you give this a quick look when you can? I don't think more testing is needed than what I already did.

[cbegeman]

I really like this change! My only question would be whether we should do the component is ocean check in ocean_io_step's __init__ rather than its methods.

[xylar]

My only question would be whether we should do the component is ocean check in ocean_io_step's init rather than its methods.

I'll look into that but I think probably so.

[xylar]

There seems to be an easier fix that I'll push in just a second.

[xylar]

@cbegeman, 07da14a seems like an elegant way to take care of this. I'm going to go ahead and merge once CI finishes but I'll test this further in my next branches I'm working on.

[cbegeman]

@xylar Yes, that looks great.