Crop CUPiD notebook

CUPiD PR at NCAR/CUPiD#180.

It's now at a state where it provides plenty of useful figures, but there is some additional support work needed before it's ready for production use.
- [ ] Add support for unstructured grids.
- [ ] Check that it works via the `cupid-` scripts, not just interactively in notebook—including publication to web.
- [ ] Merge in latest CUPiD and fix whatever that breaks.
- [ ] (Optional) "Timeseries" file generation should be integrated into our postprocessing workflow. It's not strictly necessary, though, because there is currently support for doing that postprocessing as a step in the CUPiD notebook—it just makes things _much_ slower.

Plus, of course, this is blocked by #3396. There are probably other CTSM-side things that should happen too:
- [ ] `aux_clm` test