[Redesign] Convert Dashboard Panels to ObjectBox
Summary: Moves Dashboard Panels to use PHUIObjectBoxView and PHUIHeaderView
Test Plan:
Tested the most common dashboards, Differential, Maniphest, Projects, Feed, Audit. Some edge cases (Legalpad, Macro) still are in progress. Tested laying out a new Dashboard, removing panels, moving panels.
Reviewers: btrahan, epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T8099
Differential Revision: https://secure.phabricator.com/D12873