Render unit results as Harbormaster unit messages

Summary:
Ref T8095. Same as D13377, but for unit results.

This is a bit rough and there's some duplication between this and unit results. I'll likely merge them later, but I think some of it is superficial since these iterations are still a little crude.

Test Plan:

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T8095

Differential Revision: https://secure.phabricator.com/D13378