Summary:
We need to break up the `uimanager` module in order to solve circular dependencies problem (which future diff would have otherwise).
Changelog: [Internal] Fabric-specific internal change.
Reviewed By: JoshuaGross
Differential Revision: D20885646
fbshipit-source-id: b8e3199c0eacc57a5be1481595cf97c84f972293