audio: Add vendor tags handling for AIDL

Vendor tags are used in audio attributes and in
source/sink metadata. The definition for vendor tag
syntax is the same as it used to be in HIDL.

Bug: 205884982
Bug: 272188499
Test: m
Change-Id: Iffab15edaec10f0dfccff2512bbff9dff557725a
2 files changed