Reflect worklets moving to HTML

[domenic]

See #1000. This does two things:

• Hackily redirects the worklets ED to the soon-to-be-landed HTML Standard section
• Updates references in CSS Layout API and CSS Paint API for the slightly tweaked HTML anchors

(CSS Animation Worklet and Web Audio do not seem to ever create AnimationWorkletGlobalScopes, or reference a Worklet's list of global scopes, so nothing changed there.)

Thoughts welcome on the best way to convert existing worklet spec URLs into redirects. What I did here is kind of a hack, by using a mostly-empty NOTE, because I don't know enough about your build/deploy process. Ideally there would be a server-side redirect on https://drafts.css-houdini.org/worklets/ to https://html.spec.whatwg.org/multipage/worklets.html; maybe @plinss can help with that. For making https://www.w3.org/TR/worklets-1/ redirect, I think @sideshowbarker might be able to help.

Ideal flow here:

• This gets approved
• We merge Move worklets into the HTML Standard whatwg/html#6056
• We merge this

[domenic]

Oh, another thing which would be great is if I got issue triage access to this repository, so that I could help close or move worklets-related issues. whatwg/html#6056 closes 5 open issues/PRs and I'd like to tackle several others in the near future.

[bfgeek]

lgtm - Just let me know when you want this merge'd.

[domenic]

Woohoo, ready to merge!