MediaRouter: Make MR2M.CB.onRouteSelected to be called

With this, MediaRouter2Manager.Callback.onRouteSelected will be called properly.

This CL also adds provider id to MediaRoute2Info to distinguish routes
with the same id from different providers.

Test: atest mediaroutertest

Change-Id: If353a4decad489576a39b1a93c7d99c7fe238abe