A pull request now shows when an automatic review finding is still unanswered

Every change to the platform is reviewed automatically before it can merge. Until now, nothing checked whether anyone had read that review: a change whose tests finished quickly could merge while the review's findings sat unanswered. One such change, with fourteen unread findings, stopped new plugin releases from being published for six hours.

A new check, Automatic review answered, now appears on every pull request. It stays red until:

• the automatic review has really reviewed the change — a message saying the reviewer could not review it (for example because its monthly allowance ran out) does not count, and
• every finding the review raised has a reply from a person, whether "fixed" or an explanation of why not.

If the reviewer genuinely cannot review a change, only a maintainer can release it, and the release is visible on the pull request.

For now the check is shown but does not block a merge. It becomes a requirement once it has been watched on real pull requests.