[ENH]: Propose a more balanced set of styles toward the dark side

Problem

There are a lot of proposed styles on https://matplotlib.org/stable/gallery/style_sheets/style_sheets_reference.html but most of them are light theme: a single dark theme exists against almost 30 light, and let's be honest it's not one that has received a lot of love. I submitted a quick fix to make it viable with a grid (https://github.com/matplotlib/matplotlib/pull/23598) but it's not going to fix the core issue, that is the lack of dark themes available.

The dark_background is also pretty bland: using "black" is typically the most aggressive background you could pick for a "dark" theme, it doesn't need to be.

Proposed solution

Maybe https://github.com/chriskempson/base16 (for example) could be used as a foundation for adding more dark flavors?

This is a reasonable argument, and I'd support adding a few more "dark" styles. If we do this, it would be nice to have someone who is an expert in data visualization design the styles. Perhaps a good use for a small dev grant?