R1:953ff197bf26

Allow Herald rules to be disabled, instead of deleted

Summary:
Ref T603. Ref T1279. Further improves transaction and policy support for Herald.

- Instead of deleting rules (which wipes out history and can't be undone) allow them to be disabled.
- Track disables with transactions.
- Gate disables with policy controls.
- Show policy and status information in the headers.
- Show transaction history on rule detail screens.
- Remove the delete controller.
- Support disabled queries in the…