Add color support for copy and toggle buttons

[choldgraf]

This adds color support for two more web component extensions: sphinx-copybutton and sphinx-togglebutton. It does this by adding another SCSS extensions file for each, and adds them to our docs.

[drammock]

sphinx-togglebutton seems (almost) redundant with sphinx-design dropdowns... I mean, the functionality is the same, but the styling is different because togglebuttons add that functionality to existing sphinx admonitions. I'm not sure what else to say about that other than it feels non-DRY but I guess it makes sense for the theme to work smoothly with either one? 🤷🏻

[choldgraf]

I'm not sure what else to say about that other than it feels non-DRY but I guess it makes sense for the theme to work smoothly with either one

My feeling is that this theme should support a variety of extensions and sub-packages, as long as they have active use in our stakeholder communities (PyData), and they do not require a lot of extra maintenance burden. In this case, it just means adding some special-cased CSS which shouldn't be too hard to maintain.

In the future if there is consolidation around a single package, we could re-work our CSS here to unify under a specific package, but at least for now there are multiple projects using each (for example, Jupyter Book / MyST-NB ship with sphinx-togglebutton, while Sphinx Design tends to be used more by end-users)

[drammock]

you've convinced me :)