Additional changes:
* rlModuleLoader is no longer needed now that the mediaViewerOverlay is
part of mobile.startup so that was removed in addition to the calls to
it.
* Removed the EVENT_SLIDE/EVENT_EXIT logic as the mediaViewerOverlay
now handles its own slide/exit behavior
Bug: T216198
Depends-On: I36e3c0645c931492fbef0b7c0a49f6a418dbd3a1
Change-Id: I04656c4adb7edc9a111447de3d63044044a8d6dd