Summary:
* Fabric surface hosting view should emit the same event as RCTRootView
* Before emitting to JS, make sure to check if the color scheme really changed to avoid unnecessary re-render in JS
Changelog: [Internal]
Reviewed By: mdvacca, mmmulani
Differential Revision: D18100700
fbshipit-source-id: 451199beac07cdfb3833131ee429cc151391d8dd