Bug report

Bug summary
colormaps don't have getters for under, over, bad colors (although the corresponding setters exist).
I am writing a function that accepts a colormap as an argument. I want to ensure that the colormap passed to the function has the same color for the "bad" and "under" conditions. The only way around this is to access "private" attributescmap._rgba_under,cmap._rgba_bad as shown below.

Code for reproduction

cmap=plt.get_cmap('cividis')cmap.set_bad('k')cmap.set_under('k')assertcmap._rgba_bad==cmap._rgba_under

If adding getters (for under, over, bad colors) for the colormaps sounds like a good improvement, i would be interested in submitting a PR.

Actual outcome

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Expected outcome

Matplotlib version

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