R1:bfa2abed8428

Mostly modernize lint views and delete dead code

Summary:
This is a mostly-faithful modernization of the Diffusion lint interfaces. It:

- Makes them policy aware;
- removes the last callsites for old/dead code (crumbs, nav).

It's a little rough, but should be perfectly usable. At some point this should get another pass, but probably after we make it easier to populate the lint data.

Test Plan: See screenshots.

Reviewers: btrahan

Reviewed By: btrahan

CC: aran, FacebookPOC

Differential Revision…