Give Maniphest a title glyph

Summary:
Ref T7055. Apparently we just never had one? I feel like I'm crazy. But I can't find any trace in the logs.

I'm actually not 100% sold on this being better because it's a color glyph on OSX and those feel a little out of place / tacky to me compared to the black-and-white ones. So I'd be fine with just leaving it off, too. Clearly not important if no one noticed it until I caught it in T7055.

Test Plan:

Reviewers: chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T7055

Differential Revision: https://secure.phabricator.com/D11524