Send AssistContent with current activity's intent to contentcapture.

- This change extends the current sending of ActivityEvent, to also send Intent data during activity-start.
- Internally, the call chain in ContentCapture local service is asynchronous http://shortn/_8GKsVIffiV

Context: go/aiai-intent-discovery

Bug: 344587973
Test: manual - Checks if the activity-start AssistInfo are received by
    ContentCaptureService in AiAi.
Test: added cts in topic.
Test: atest ActivityRecordTests

Change-Id: Ic61f1a6a401d742e1a364cb71b1814dc9a651a47