R1:4c66a92f9246

Port Repository "Branches" to new UI

Summary: Ref T10748. Makes a "Branches" panel, enables these transactions in the EditEngine.

Test Plan:
- Edited via EditEngine + Conduit.
- Viewed via manage UI.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10748

Differential Revision: https://secure.phabricator.com/D15809