## Summary
Replace color/dark-color pairs in components with design tokens to allow
for easy overriding.
<!-- Also standardizes the icon pattern to simplify the tailwind config.
-->
## Changes
- **What**: Token based colors, for now, mostly.
- **Breaking**: Got approval from Design to collapse some very similar
pairs of colors that seem to have diverged in implementations over time.
Some of the colors might be a little different, but we can tweak them
later.
## Review Focus
Still have quite a few places from which to remove `dark-theme`, but
this at least gets the theming much closer.
Need to decide if I want to keep going in here or cut this and do the
rest in a subsequent PR.
## Screenshots (if applicable)
<!-- Add screenshots or video recording to help explain your changes -->
┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-5908-WIP-Make-components-themeable-2816d73d365081ffbc05d189fe71084b)
by [Unito](https://www.unito.io)
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Co-authored-by: github-actions <github-actions@github.com>
