Define an extensible audio channel layout description

The new way for describing audio channel layouts which can
be used both in framework <-> framework and framework <->
HAL interfaces and directly supports extensions by vendors.

The mapping is defined between the legacy audio_channel_mask_t
and the new descriptions.

Bug: 188932434
Test: atest audio_aidl_conversion_tests
Change-Id: I23e387b2424e1d07a7637a2797f0e905a02feab1