Refactor AudioEffect callback to interface

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

 - Removes need for event enum, user cookie, and opaque arg
   ptr.
 - Replace effect_callback_t with IAudioEffectCallback 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: Id75c8866bdfa528d37cf1f93e41e917568c4a147
Bug: 199156212
Test: Compiles. To be verified.
Change-Id: I6e49abd463196c1e89f3ca0578e9cd84c5a7f89e