R1:df6ad0756694

Add DiffusionBranchListView for browsing branches

Summary: Adds a new DiffusionBranchListView which replaces the BranchTable when browsing all branches in Diffusion. Has all the same capabilities, but is easier to read, adds a Compare button, and plays nicely on mobile. It does take up more space, but I think that's generally OK here since we expect our branches to not be heaping piles of intern revert branches.

Test Plan:
Follow a few repositories with branches, like Phabricator and KDE's Krita. View…