AudioService: Add the service's message queue to the dump

Clogged queue means UI and other commands can not reach
the service and will cause volume controls to malfunction.

Example dump snippet:

Message handler (watch for unhandled messages):
  Handler (com.android.server.audio.AudioService$AudioHandler) {a904698} @ 61825
    Looper (AudioService, tid 118) {6808ef1}
      Message 0: { when=-52s689ms what=25 ... }
      Message 1: { when=-52s8ms what=8 ... }
      Message 2: { when=-52s4ms what=8 ... }
      ...
      Message 35: { when=-2s436ms what=0 ... }
      (Total messages: 36, polling=false, quitting=false)

This indicates that the command queue is not being processed
because the handler got stuck. Checking stacks of the system_server
can help in figuring out the reason.

Bug: 135763139
Test: adb shell dumpsys audio
Change-Id: I02009720668af218edb38d5a5948a5964b72c685
Merged-In: I02009720668af218edb38d5a5948a5964b72c685