Summary: Ref T4327. At some point these two very similar classes got introduced. Collapse `DiffusionBranchInformation` into the nearly identical `DiffusionRepositoryRef`, which enjoys slightly more generality and support.
Test Plan: Viewed branch overview and detail pages. Ran `repository refs` and `repository discover`. Grepped for removed symbols.
Reviewers: btrahan
Reviewed By: btrahan
CC: aran
Maniphest Tasks: T4327
Differential Revision: https://secure.phabricator.com/D8002