Add a mechanism for configuring the A2DP Source codecs

* Extended the Bluetooth A2DP AIDL interface to get/set the current
  codec configuration

* If the current codec config is changed such that the audio feeding
  parameters have changed, then inform the Audio Manager so it can
  reset accordingly the audio feeding parameters in the Audio HAL to
  the Bluetooth stack.

Also, fix the BT_BOND_STATE_* values (unused) in the
AbstractionLayer.java class so they match the corresponding
BT_BOND_STATE_* values in
hardware/libhardware/include/hardware/bluetooth.h

Test: A2DP streaming to headsets, TestPlans/71390
Bug: 30958229
Change-Id: Ic3e35154d9dbc32b66522322cd5d2a96bc5a977c