WIP: refactor model2netcdf.ED2

[Aariq]

Description

There are a few bugs and some design fragility in model2netcdf.ED2() that I think warrant a pretty substantial overhaul. I'm going to work on that in this PR.

Issues I hope to address:

• https://github.com/PecanProject/pecan/issues/3069
• https://github.com/PecanProject/pecan/issues/3068
• https://github.com/PecanProject/pecan/issues/2102
• https://github.com/PecanProject/pecan/issues/774 (maybe)

Motivation and Context

Ran into a weird edge case with model2netcdf.ED2() and remembered what a quagmire it felt like to me last time I worked on it. I feel like I have a better handle on working with lists and ncdf4 that I can simplify this function a lot while making it easier to expand in the future.

Review Time Estimate

• [ ] Immediately
• [ ] Within one week
• [ ] When possible

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [ ] My change requires a change to the documentation.
• [x] My name is in the list of CITATION.cff
• [ ] I have updated the CHANGELOG.md.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.