Fix synchronization issues in AlwaysOnHotwordDetector

- Remove unnecessary recognition status from AlwaysOnHotwordDetector

- Remove unnecessary recognition started callback from IRecognitionStatusCallback

- Fix a bug around the fact that we weren't picking up enrollment at runtime because
we were storing the availability at instantiation time.

- Handle 0-length arrays in SoundTrigger classes while parceling/unparceling

- Fix issue in SoundTrigger helper where we were not comparing binders for start/stop calls

- Unload the previous model when starting a new recognition

- Add more debug logging

Change-Id: Icc56d7f3dd1ffa49a8cfeea49080e3ab4d342c32