Add InputRouteManager and InputMediaDevice to support input routing

InputRouteManager interacts with AudioManager to get/observe
available input routes.

Change-Id: I5503aa3f7a51420c0af87ca225c03818e8451056
Bug: b/355684672, b/357122624
Test: atest MediaOutputControllerTest, LocalMediaManagerTest
      atest InputRouteManagerTest, InputMediaDeviceTest
Flag: com.android.media.flags.enable_audio_input_device_routing_and_volume_control