change DifferentialRevisionDetailView to use newer fangled UI abstractions

Summary: actions are still a bit messy - unsatisfactory icons (T2013 will help!)

Test Plan: viewed diffs - they look good

Reviewers: epriestley, vrana

Reviewed By: epriestley

CC: chad, aran, Korvin

Maniphest Tasks: T2007

Differential Revision: https://secure.phabricator.com/D3904