Refactor AudioRecord callback to interface

Refactor AudioRecord callback from static function pointer
with pointer args to callback interface.

 - Removes need for event enum, user cookie, and opaque arg
   ptr.
 - Replace callback_t with IAudioRecordCallback listener interface for
   separate notifications for each event type.
 - Duplicate set/constructor methods to provide for incremental
   refactor.
 - LegacyCallbackWrapper to wrap legacy_callback_t consuming methods
 - Retain wp<IAudioTrackCallback> to refcount and avoid ownership
   cycles.

Related-to: I67dc284307419737eeb055db851751455abf103d
Bug: 199156212
Test: Compiles. To be verified.
Change-Id: Id75c8866bdfa528d37cf1f93e41e917568c4a147