Support Audio common AIDL NDK conversion

Split libaudioclient AidlConversion into two:
1. Conversion methods of libaudioclient AIDL definitions stays in
   libaudioclient and only support CPP backend (default) conversion.
2. Conversion methods of common AIDL definitions (which can be used by
   HAL) in common folder and support both CPP (default) and NDK (define
   BACKEND_NDK in CFLAGS) backend conversion.

Bug: 261129656
Test: Build flash andi run audio use cases on Panther

Change-Id: I62c95b95ad12fa9a9d3f48f3505241637a7e817a