Show "Tnnn" crumb on Edit Task screen

Summary: Fixes T4198. We don't currently show "(Maniphest) > T123 > Edit" on the edit screen, which is inconsistent. Add the "T123" crumb.

Test Plan: {F87177}

Reviewers: chad, btrahan

Reviewed By: chad

CC: aran

Maniphest Tasks: T4198

Differential Revision: https://secure.phabricator.com/D7699