DiffusionBranchQuery => Conduit

Summary: ref T2784. This one had a few fun spots where I had to move data around. Also, is there some common object (or should I add it?) that can do this toDictionary newFromConduit stuff? Also, this assumes D5803 is largely correct at the time of this diff.

Test Plan: browsed mercurial and git repository page. saw the branches i expected.

Reviewers: epriestley

Reviewed By: epriestley

CC: chad, aran, Korvin

Maniphest Tasks: T2784

Differential Revision: https://secure.phabricator.com/D5810