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:

• wrong dimensions assigned for some variables by model2netcdf.ED2() #3069
• model2netcdf.ED2() gives incorrect output when PFT is in settings but not in ED output #3068
• Generalize creation of variables in models/ed/R/model2netcdf.ED2.R  #2102
• Latent heat for ED2 #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.
• My name is in the list of CITATION.cff
• I have updated the CHANGELOG.md.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.