Add UtteranceProgressListener#onStop callback

New UtteranceProgressListener callback that allows
to detect a call to TextToSpeech#stop() (or QUEUE_FLUSH usage)
from the same client, or a QUEUE_DESTROY usage from any other
client (Talkback uses it to preempt other users of TextToSpeech
queue). This change is required for seamless Books read aloud
feature+Talkback usage.

+ Fixes for broken tests/TtsTests

Bug: 17901521

Change-Id: I30d2f297bb7c8d05cbeb16f63e85c1be0cca5c84