async enrollment support AlwaysOnHotwordDetector

Added ability for AlwaysOnHotwordDetector to support async enrollment
performed outside of support detected through KeyphraseEnrollmentInfo.

Bug: 147159435
Test: tested enrollment and availability is updated when enrolling
outside of KeyphraseEnrollmentInfo

Change-Id: Ia5d71e90c062ac100d4c6df760acf0d41920853e