Fully modularize DestructionEngine
Summary: Ref T9979. Convert all DestructionEngine behaviors to extensions.
Test Plan:
Destroyed an object, verifying:
- Herald transcripts were destroyed;
- edges were destroyed;
- flags were destroyed;
- tokens were destroyed;
- transactions were destroyed;
- worker tasks were cancelled.
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T9979
Differential Revision: https://secure.phabricator.com/D14832