Batch tracked users setup

[Half-Shot]

The intention here is to handle things when thousands of requests are made to add tracked users and the async lock gets dogpiled. Async lock has a (sensible) limit of 1000 acquires before it gives up, so I think we should just queue up requests in a big batch and handle them like so.

Checklist

• Tests written for all new code
• Linter has been satisfied
• Sign-off given on the changes (see CONTRIBUTING.md)

[AndrewFerr]

Good idea.
My only request is an optional one for performance reasons, but this looks functionally correct as it is.

[AndrewFerr]

Might be worth avoiding creating an extra array with the spread syntax.

Something like this should work:

Suggested change

	const uids = [...this.trackedUsersToAdd].map(u => new UserId(u));
	const uids = Array<UserId>(this.trackedUsersToAdd.size);
	let idx = 0;
	for (const u of this.trackedUsersToAdd.values()) {
	uids[idx++] = new UserId(u);
	}

[AndrewFerr]

Oh, and if you don't mind, rebase this directly onto upstream main before merging, since this could be PR'd into upstream too.