polaris-viz package

[xylar]

@andrewdnolan proposed that we consider a separate visualization package for Polaris.

The idea would be:

1. to pull out pieces of the existing functionality in https://github.com/E3SM-Project/polaris/tree/main/polaris/viz
2. to make some of the "private" functionality public (e.g. making matplotlib patches from an MPAS mesh)
3. to add new functionality as needed (e.g. as MPAS-Analysis gets ported to Polaris)

One motivation is to make it easier to use these features outside of Polaris (e.g. for figures for papers) without having to copy and paste code.

polaris-viz is merely a strawman name for the package. That's up for discussion.

[xylar]

@andrewdnolan, I've had time to think about this more and I like the idea.

It would give you a chance to have a package you design, which would be good experience for you.

It would also give us a chance to bring together and clean up functionality that is currently scattered in several places:
https://github.com/MPAS-Dev/MPAS-Tools/tree/master/conda_package/mpas_tools/viz
https://github.com/MPAS-Dev/MPAS-Tools/tree/master/conda_package/mpas_tools/ocean/viz
https://github.com/MPAS-Dev/MPAS-Analysis/tree/develop/mpas_analysis/shared/plot
https://github.com/E3SM-Project/polaris/tree/main/polaris/viz

It's a little bit of a pain to co-develop package (e.g. polaris and polaris-viz) so we would have to keep that in mind. But it would also allow the viz to be used outside of Polaris, which is currently quite difficult.