Bring muse_dev up-to-date with version 4.x

[kbwestfall]

This would merge the current develop branch into muse_dev and institute all the changes we talked about for the front end and the new method used to run the DAP.

There were a few conflicts that I had to deal with, but nothing looked unclear. The specific files with conflicts were:

mangadap/proc/spectralstack.py
mangadap/proc/spatiallybinnedspectra.py
mangadap/scripts/spotcheck_dap_maps.py
mangadap/dapfits.py
mangadap/util/fitsutil.py

So I would pay particular attention to changes made there.

The only thing that might be questionable is the check that there are no NaNs in the DAP output files, which is done in mangadap/scripts/spotcheck_dap_maps.py. We just need to check that this now works, or comment out the code again. Note the comment I left in the file.

I expect fit_one_cube_muse.py is broken in this branch because mangadap.par.analysisplan has moved to mangadap.config.analysisplan, and the instantiation is different. As I said earlier, I'll send along the KCWI example I've been working with, and I'll also use the plan you have in fit_one_cube_muse.py to construct a new plan toml file that should do the same thing.