We've been doing great with gradient colormaps, but I'd like more options for customizing/accessing indexed palette colormaps. For example I'm working on a Mel scaled spectrogram (swharden/Spectrogram#14), but it's not super easy for me to change the default colors of the triangles.

This is the whole colors module, and I think we can do better by taking inspiration from the recent colormap improvements.
https://github.com/swharden/ScottPlot/blob/6d585f5c174c3218099b8ed2ed7400f24cb002d6/src/ScottPlot/Config/Colors.cs#L8-L30

I don't think we should add palette colors to the Colormap module, instead we should have a ColorSets module. This may require some thinking/experimenting to design well...