Initial implementation of the IntelligenceService pipeline.

It's still full of TODOs, but at leats it now provides an end-to-end
workflow from the activity creation / destruction to the service implementation.

Test: mmm -j packages/experimental/FillService && \
      adb install -r ${OUT}/data/app/FillService/FillService.apk && \
      adb shell settings put secure intel_service foo.bar.fill/.AiaiService
Bug: 111276913

Change-Id: Id5daf7b8b51e97c74d9b6ec00f953ddb02b48e46