Ambient Activation p2.1

Using voice-activation ops OP_SANDBOX_TRIGGER_AUDIO for voice acitivation
of the assistant app.
1) This change is currently flag protected by a static boolean
   IS_VOICE_ACITVAITON_OP_ENABLED. Will be converted and conform to the
   trunk stable flag configuration in a follow-up change.
2) OP_RECORD_AUDIO_HOTWORD is replaced by
   OP_RECEIVE_SANDBOX_TRIGGER_AUDIO for noting the discrete event of voice activation of
   the assistant app.

Bug: 287264308
Test: presubmit
Change-Id: I09fb4e3bc0493571a9c7f15bc84c106a127c7588