R1:ceb7f830a42d

Make HeraldRuleQuery policy-aware

Summary: Ref T2769. dem policy checks

Test Plan: Loaded `/herald/`; loaded rule editor.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran

Maniphest Tasks: T2769

Differential Revision: https://secure.phabricator.com/D6650