Summary:
Ref T12174. This fixes more bugs than it creates, I think:

  - Dashboards now show the whole menu.
  - Project and home items now show selected state correctly.
  - The "choose global vs personal" thing is now part of MenuEngine, and the same code builds it for Home and Favorites.
  - Home now handles defaults correctly, I think.

Maybe regression/bad/still buggy?:

  - Mobile home is now whatever the default thing was, not the menu?
  - Title for dashboard content or other items that render their own content is incorrectly always "Configure Menu" (this was preexisting).

Test Plan:
  - Created, edited, reordered, disabled, deleted and pinned personal and global items on home, favorites, and projects.
  - Also checked User profiles.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T12174

Differential Revision: https://secure.phabricator.com/D17273