Separate the repository management UI into sections

Summary: Depends on D19826. Ref T13216. We have a fair number of options here; add some groups so the "Build" stuff can go in a little subcategory and such.

Test Plan:

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13216

Differential Revision: https://secure.phabricator.com/D19827