For patches, EWS will set "cq-" when a patch encounters a failure that should block landing. For pull requests, we should have something similar, but "changes requested" isn't nearly as strong as "cq-". Adding the "blocked" label, which acts similar to "cq-".
<rdar://problem/89689094>
Pull request: https://github.com/WebKit/WebKit/pull/182
Landed https://commits.webkit.org/248233@main (r291060)!