SoundTriggerHelper changes for GenericSoundModels.

 - Refactoring SoundTriggerHelper to handle generic sound models.
     - Ability to store multiple models, callback and state information.
     - Separate out initialization to be done per voice model, per any model
     and per generic model.
 - Minor change to the API exposed -- removing the Handler from the
   createSoundTriggerDetector call.
 - Added callback processing for onRecognitionEvent().
 - Added logic for stopAll().
 - Changes to the SoundTriggerTestApp to start/stop recognition.
     - Multiple models (3).
     - Ability to start/stop/load/unload individual models.

Bug: 22860713
Bug: 27222043
Change-Id: Ie5d811babb956bead653fb560a43f1e549ed11bd