Expose task id and activity component in task snapshot and assist structure

- This would allow the AiAi service to cross-reference assist data with
  streaming text data and snapshots
- Pre-fill the task id/activity when receiving the assist data from the
  activity and remove unnecessary autofill santization down the line

Bug: 117268952
Test: adb shell dumpsys window all
Test: atest CtsAutoFillServiceTestCases
Test: atest CtsAssistTestCases

Change-Id: I0d0d2c85426777cc77397716db34b520593db100