Show additional details for failed builds in Harbormaster

Summary:
Ref T10457. When tests fail, it currently takes several clicks to figure out why they failed.

In this project, map rebuilds and liberate are fairly common failure conditions, but verifying that they were the root issue requires jumping into a build, then scrolling through a log.

Instead, display details if they're available.

Test Plan:
Before:

{F1135453}

After:

{F1135454}

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T9951, T10457

Differential Revision: https://secure.phabricator.com/D15363