Summary:
Fix T9662.
Record who initiated the build, and allow this information as a parameter.
In this implementation, a 're-run' keeps the original initiator, which we maybe not desired?
Test Plan:
Make a HTTP step with initiator.phid, trigger manually, via HM, via ./bin/harbormaster build.
Look at requests made.
Reviewers: epriestley, #blessed_reviewers
Reviewed By: epriestley, #blessed_reviewers
Subscribers: Korvin
Maniphest Tasks: T9662
Differential Revision: https://secure.phabricator.com/D14380
