Load global and custom profile menu items in a single query

Summary: Ref T5867. Use a single query to load both personal and global items, then reorder them and add a divider if both groups have some stuff.

Test Plan: Viewed menu, edited personal and global items, viewed/edited existing project menus.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T5867

Differential Revision: https://secure.phabricator.com/D17213