Support querying Herald rules by monogram in typeahead datsources

Summary:
Depends on D19556. See PHI765. Ref T13164. Currently, if you type H1 in this datasource, it isn't smart enough to pull up the right object.

Add support for querying by monogram. This is similar to existing support in Owners packages, etc.

Test Plan: Typed H1 in the new push log filter, got the right object as a result in the typeahead.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13164

Differential Revision: https://secure.phabricator.com/D19557