AudioService: history of A2DP commands

Keep history of command coming from A2dpService in AudioService
  logger.

Bug: 110186160
Test: connect/disconnect A2DP device and take bugreport,
      or run $ adb shell dumpsys audio

Change-Id: Ice65c20e91aa2675fbacb1c326a53d5b02bba3e5
(cherry picked from commit 3bf75781)
Merged-In: Ice65c20e91aa2675fbacb1c326a53d5b02bba3e5