Summary:
Ref T4264. This gets most of the plumbing in for "object" rules, which will bind to a specific object, like a repository or project.
It does not yet let you actually create these rules.
Test Plan: Ran `storage upgrade`, created/edited rules, browsed Herald.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T4264
Differential Revision: https://secure.phabricator.com/D7847
