Rough in basics + policies + history repository management panels

Summary:
Ref T10748. This is roughly where I'm headed, if it makes some kind of sense? The "Edit" links in sub-sections don't work yet since I haven't built the thing.

Probably depends on D15736.

Test Plan: Manually navigated to /manage/, clicked around.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10748

Differential Revision: https://secure.phabricator.com/D15737