A2DP related API update and cleanup

* Added new A2DP API and use it as appropriate
  - A2D_GetTrackFrequency()
  - A2D_GetTrackChannelCount()
  - A2D_GetNumberOfSubbands()
  - A2D_GetNumberOfBlocks()
  - A2D_GetAllocationMethodCode()
  - A2D_GetChannelModeCode()
  - A2D_GetSamplingFrequencyCode()
  - A2D_GetSinkTrackChannelType()
  - A2D_GetSinkFramesCountToProcess()

* Added corresponding unit tests for the new API

Also, A2DP related cleanup:
 - Renamed A2D_sbc_dump_codec_info to A2D_DumpCodecInfoSbc()
 - Changed the order of tA2D_SBC_CIE.min_bitpool and
   tA2D_SBC_CIE.max_bitpool to reflect the order of the corresponding
   fields in the Bluetooth spec (A2DP spec v1.3, page 21).
 - Added new API A2D_GetMediaType() and the corresponding unit test
 - Renamed AVDT_MEDIA_AUDIO to AVDT_MEDIA_TYPE_AUDIO
 - Renamed tA2D_SBC_CIE.alloc_mthd to alloc_method
 - Renamed A2D_BAD_ALLOC_MTHD to A2D_BAD_ALLOC_METHOD
 - Renamed A2D_NS_ALLOC_MTHD to A2D_NS_ALLOC_METHOD
 - Eliminated usage of A2D_MEDIA_TYPE_AUDIO and replace it with
   AVDT_MEDIA_TYPE_AUDIO.
    Now the media_type value everywhere is the AVDT_MEDIA_TYPE_* value
    without the reserved 4 bits (LSBs).
 - Fixed macro defines in file "stack/avdt/avdt_defs.h"

Bug: 30958229
Change-Id: Id82653e9c9460aeb92d942a9179bb5abdb4bfdec