Summary:
Depends on D20405. Ref T13272. Currently, the `PhabricatorDashboardLayoutConfig` class uses a lot of `switch()` statements to define layout modes.
Although I'm not planning to add thousands of new layout modes, this (and upcoming changes) can be made substantially cleaner by using a standard modular approach.
(This doesn't fully remove `PhabricatorDashboardLayoutConfig` yet, but that will happen soon.)
Test Plan: Edited a dashboard, saw the same layout modes as before.
Reviewers: amckinley
Reviewed By: amckinley
Maniphest Tasks: T13272
Differential Revision: https://secure.phabricator.com/D20406
