expose HAL keyphrase trigger extras to EventPayload

The SoundTrigger HAL can deliver additional context about the kephrase
that was triggered along with the trigger audio. This change moves to
expose the information which was previously suppressed by the Android
framework.

Data exposed:
- Keyphrase extras providing details on what phrase was interpreted by
the voice engine

Extra keyphrase information provided by the SoundTrigger HAL which was
previously suppressed is also exposed.

Test: atest AlwaysOnHotwordDetectorEventPayloadTest
CTS-Coverage-Bug: 215375531
Bug: 215066299
Change-Id: I3b20fd3692c3f9c86181f87d66622c77778b9ab2