Mod action logs don't escape formatting in usernames

Usernames with multiple underscores in them may result in italics (or potentially a removal of bold text) in moderator action logs. Appears to only affect people with an underscore followed/preceded by a period or an underscore at the end.

No file or test is named in the issue. Locate the moderator action-log formatting entry point and reproduce the problem with usernames containing multiple underscores, periods, or a trailing underscore. Done means those usernames display literally without changing italics or bold formatting.

Written by the indexing model from the issue text.