Move the view of merged changes to "DiffusionCommitGraphView"
Summary: Ref T13552. When viewing a merge commit, merged changes are currently shown inline. Update this view to use the new "GraphView" rendering pipeline.
Test Plan:
- Viewed a merge commit, saw merges.
- Viewed history, profile page, etc.
Maniphest Tasks: T13552
Differential Revision: https://secure.phabricator.com/D21413