audio: Show microphone icon when input device is connected

screenshot: https://screenshot.googleplex.com/6hs9sFLEx8Zv75y

Test: atest MediaOutputAdapterTest
Flag: com.android.media.flags.enable_audio_input_device_routing_and_volume_control
Bug: b/355684672
Change-Id: I1cecc4f442df055ac4626e15ebe01d8656aa55eb