Decouple MediaRouter2Manager from MediaDevice

The required routing methods are now available through InfoMediaManager,
still decoupled from MediaRouter2Manager.

This is a non-functional change.

Bug: 192657812
Test: atest InfoMediaManagerTest MediaDeviceTest LocalMediaManagerTest
Change-Id: Idbb22a8c4ebb790f2b0a3ba011d6aa1a1be56550