R1:23e68ee8cb44

Use ApplicationSearch in ReleephBranchView

Summary:
Ref T3721. Releeph currently attempts to implement a flexible, field-driven search for branches, but it's building all of its own infrastructure and it ends up heading down some weird paths. In particular, it loads **every** request and then makes calls into fields to filter them. It also tries to be very very general, which isn't really necessary (for example, I think it's reasonable for us to assume that we won't let you disable the "requestor" field).