🛠️ Cleanup: Integrate more properly with GitHub's design system

[JoshuaKGoldberg]

GitHub uses a few web components to set up the Saved Replies dropdown: details-menu, fuzzy-list, and so on. That makes it a little tricky to manipulate their DOM manually the way this extension currently does.

It would be nice if this could instead use whatever APIs -if any?- those web components expose to more properly manipulate their contents. Then this extension's added replies would be more seamless -- and support keyboard extensions!

[JoshuaKGoldberg]

Confirmed on a Twitch stream chat that in theory one should be able to use the Primer React components or the Web Components + correct classes (thanks @keithamus!). I'm going to run with the assumption that this is technically doable. Marking as accepting PRs!

Note (also thanks again, haha) the specifics of which components are named what do change over time. E.g. details-menu, fuzzy-list, etc. are changing. I'll try to remember to update this issue as PRs come into this repo.

[JoshuaKGoldberg]

I tried adding an import { ActionList } from "@primer/react" to the main content script. It crashes with:

Uncaught TypeError: Cannot read properties of null (reading 'get')`

...on this line of code inside the GitHub code:

customElements.get("live-region") || customElements.define("live-region", kl);

Turns out custom elements just plain aren't allowed in Chrome extensions: https://issues.chromium.org/issues/41118431

...so this issue is blocked on either:

• Chrome extensions allowing custom elements
• GitHub's code abandoning all uses of them

shakes fist at web components