Land Diagnostics using ADF

[wwieder]

This is a draft PR, but hopefully offers a place to start working on using the ADF framework to make land model diagnistics

[wwieder]

OK, as a baseline, it seems like this is ready for review. I do worry that some of the changes we made may break ADF functionality on the CAM side, so maybe it's worth testing / trying this out with this concern in mind?

[brianpm]

Just a note that I've been experimenting this week with sending CAM-SE native files through ADF. At this point I have some prototype code that does a very similar xESMF regridding step as is included here. So it there could be some potential iteration on that to generalize the regridding steps so both CAM and CLM can use the same functions.

[wwieder]

@brianpm that would be excellent. There are some particular things that we have to do to properly weight grids by their landfraction for CLM output, but hopefully much of the basic regridding functionality can be more generalized.