Allow task graph task titles to go full width

Summary: Fixes T12213. Removes truncation and allows titles to be full width if needed.

Test Plan:
Chrome / Firefox / Safari on Mac, mobile and desktop widths.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12213

Differential Revision: https://secure.phabricator.com/D17336