Improve consistency in use of "via", "objectPHID", and "containerPHID" parameters in repository workers
Summary:
Ref T13591. Improve how parameters are passed between commit worker tasks:
- Always pass "via", to track where tasks came from.
- Always provide "objectPHID" (with the commit PHID).
- Always provide "containerPHID" (with the repository PHID).
Test Plan:
- Pushed a new commit.
- Ran `bin/repository pull` + `bin/repository discover`, saw commit with all parameters.
- Ran `bin/worker execute ...`, saw a Change worker and then a Publish worker with appropriate parameters.
- Ran `bin/repository reparse ... --background`, saw workers queue with appropriate parameters.
Maniphest Tasks: T13591
Differential Revision: https://secure.phabricator.com/D21532