Modernize Herald

Summary: Updates Herald to use modern methods.

Test Plan: View List, View Test Console, Run a test, View Results, View Rules, New Rule, Edit Rule, Check mobile menus.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9690

Differential Revision: https://secure.phabricator.com/D14596