Users (who aren't whitelisted) who post top-level to an proposal should have their comment automatically moved to a PR review comment

The Spec Core Team often has the manual task of cleaning up comments that appear from contributors at the top-level of the MSC (a PR comment, rather than a PR review comment). Cleaning them up involves copying the contents of the comment, hiding it, then starting a new thread on the MSC (typically at line 1) and pasting the contents there as a quote. Along with some text to inform the user as to why it was necessary.

This is time-consuming manual work. And sometimes when we don't catch these comments quickly enough, other people will reply with another top-level comment, making the problem worse.

It would be nice if mscbot could take care of doing that automatically, along with a canned explanation. It should support a config option that excludes certain users (SCT, guardians, MSC author) who occasionally do need to post top-level from the correction.

No file, test, or entry point is named in the issue. Start by locating the code that handles GitHub pull-request comments and configuration, then trace how top-level comments and user exclusions are represented. Done means eligible comments are moved into review threads with the canned explanation while excluded users are unaffected.