R1:c35cafda2c2f

Use ChangesetListView on Differential standalone view

Summary:
Fixes T4452. Ref T2009. There's a hierarchy of changeset rendering power: only low-level calls, use of ChangesetDetailView, then use of ChangesetListView (a list of DetailViews).

Prior to work here, the various changeset rendering controllers got their hands dirty to varying degrees, with some using only the lowest-level rendering pipeline:

- Phriction: no view (lowest level)
- Diffusion: DetailView
- Differential Changeset: DetailView…