The old approach was incomplete. Hook env vars are now:
* persisted and restored between agent restarts
* deterministic (LWW if 2 hooks set the same key)
* Migrated all of the old leader task tests and got them passing
* Refactor and consolidate task killing code in AR to always kill leader
tasks first
* Fixed lots of issues with state restoring
* Fixed deadlock in AR.Destroy if AR.Run had never been called
* Added a new in memory statedb for testing
