Summary: Ref T4103. This starts breaking out settings in a modern way to prepare for global defaults.
Test Plan:
- Edited diff settings.
- Saw them take effect in primary settings pane.
- Set stuff to new automatic defaults.
- Tried to edit another user's settings.
- Edited a bot's settings as an administrator.
{F1669077}
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T4103
Differential Revision: https://secure.phabricator.com/D15995
