Organize bulk edit actions into nice groups

Summary: Ref T13025. We're getting kind of a lot of actions, so put them in nice groups so they're easier to work with.

Test Plan: {F5386038}

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13025

Differential Revision: https://secure.phabricator.com/D18880