Summary: Fixes T3872. Ref T1812. Ref T3886. Modernize the "closes x as y" string parser, and use all the new parsers instead of the old ones.
Test Plan: Made a commit full of a pile of these trigger strings, then used `scripts/repository/reparse.php --message` to reparse it. Verified that parses came back as expected using a bunch of `var_dump()`.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T1812, T3872, T3886
Differential Revision: https://secure.phabricator.com/D8263