Summary:
Depends on D19278. Ref T13110. This moves most of the structural logic for publishing builds to BuildableEngine and provides a `bin/harbormaster publish` to make publishing easy to retry/debug.
This intentionally removes the bit which actually does anything when builds publish. Followup changes will implement application-specific versions of the publishing logic in Differential and Diffusion.
Test Plan: Ran `bin/harbormaster publish Bxxx`, saw it do nothing (but not crash).
Subscribers: PHID-OPKG-gm6ozazyms6q6i22gyam
Maniphest Tasks: T13110
Differential Revision: https://secure.phabricator.com/D19279
c20b4e365b