PR Summary

Setting the over/under/bad when calling _resample or reverse on the colormaps.

Fixes part of #16296
Addresses bullet 3 of this comment: #16296 (comment)

Could possibly be made a little more elegant using #14645
However, when I was working through this it isn't quite so simple as calling set_over() on the new_cmap object because you're calling it with None which can't be converted to a color on the other side. You also can't update thenew_cmap. _lut directly because when generating the cmap_d the _lut of all colormaps is not populated initially and it is still calling reverse().

PR Checklist

• Has Pytest style unit tests
• Code is Flake 8 compliant
• New features are documented, with examples if plot related
• Documentation is sphinx and numpydoc compliant
• Added an entry to doc/users/next_whats_new/ if major new feature (follow instructions in README.rst there)
• Documented in doc/api/api_changes.rst if API changed in a backward-incompatible way