This is still far from perfect given the limitations of the Storybook web components package, but I figured this was worth putting up since it's still an improvement over the current state of our args tables (I think).

I'm mostly leaving the default generated `custom-elements-manifest.json` alone save for filtering some internal properties we don't want documented since they shouldn't really be accessed directly. If it seems too strange to just have the `aria-label` attr documented we could possibly remove `attributes` from the docs for now (this happens because it's the only attr where the name is different from the property name).

Open to feedback/thoughts on if this is useful or too wonky for now given the weirdness around how Storybook creates naming collisions.

Differential Revision: https://phabricator.services.mozilla.com/D162599