Allow "harbormaster.sendmessage" to send control command (pause, restart, abort, resume) to Builds/Buildables
Summary: Ref T13072. Expand the role of "harbormaster.sendmessage" and allow it to send control messages to Builds and Buildables.
Test Plan: Read documentation, sent commands to Builds and Buildables, hit a bunch of error cases, will deploy to catch full-lifecycle Build Target use cases.
Maniphest Tasks: T13072
Differential Revision: https://secure.phabricator.com/D21698