Separate revision list rendering logic into a RevisionListView

Summary: I want to throw this in Diffusion as part of T262, but it's embedded in
the controller right now. Split it out.

Test Plan: Looked at various revision list views, no changes.

Reviewers: jungejason, nh, tuomaspelkonen, aran

Reviewed By: jungejason

CC: aran, jungejason

Differential Revision: 977