audio: Add a build flag for the framework to use CAP via AIDL HAL

Enables use of Configurable Audio Policy via AIDL HAL. When the
flag is 'false' the framework falls back to loading the CAP config
directly from the vendor partition (as it used to be with HIDL).

See go/port-cap-to-aidl-audio-hal for the justification to use
a build flag.

Bug: 364310317
Test: m
Change-Id: I270846b0e5eb36b471e3db56b1a0e0c9c4713429