Summary:
In this diff I'm introducing IViewGroupManager to extract methods required to add/remove views from a viewGroup
This will be used by ViewManagers that require to add views but don't depend on ViewGroupmanager
changelog: [internal] internal
Reviewed By: javache
Differential Revision: D41386920
fbshipit-source-id: a7d893d92d0f12766dcc71dfd1b22539c3b9687d
