Create unit test framework for audio_a2dp_hw
Create unit test framework for audio_a2dp_hw and implement a unit test
for function audio_a2dp_hw_stream_compute_buffer_size()
Also:
* Remove obsolete check for mixer unit size inside out_get_buffer_size()
* Reorganize the file structure inside directory audio_a2dp_hw/ :
- Moved the source code files *.cc to audio_a2dp_hw/src/
- Moved the header file(s) *.h to audio_a2dp_hw/include/
- The unit test file(s) are stored in audio_a2dp_hw/test/
Bug:
35849921
Test: This is the unit test. Code compilation and unit test succeed
Change-Id: I3dcc508cb6799462b7103cb2ee452b4399843899