Add Assistant Triggered EventTime

Test: ADT3 on adt3-userdebug, with RVIS as the default AssistService and
VoiceInteractionService reporting the intent extra.

12-09 17:16:19.826  8809  8809 I #AssistSession: TVTS_RVIS android.intent.extra.TIME: 926771
12-09 17:16:19.826  8809  8809 I #AssistSession: TVTS_RVIS invocation_time_ms: 926773
12-09 17:16:19.826  8809  8809 I #AssistSession: TVTS_RVIS ASSIST_INPUT_DEVICE_ID: 7
12-09 17:16:19.826  8809  8809 I #AssistSession: TVTS_RVIS invocation_phone_state: 5
12-09 17:16:19.840  8809  8809 I #AssistSession: [TVTS] Showing Voiceplate: 926792
12-09 17:16:19.932  8809  8832 I AudioSourceManager: [TVTS][Legacy] micOpen
12-09 17:16:20.162  8809  8856 I AudioSourceManager: [TVTS][Legacy] Read non-zero bytes

Bug: 129355484

Change-Id: I653deac41e105e04f56e03aec0fa80d8d7eb5b54