Reset app reporting on app launch.

Store the reported changes by app and clear the app info on app launch.
This means that changes reported to the system server would be logged
once per app launch instead of once per device boot.

Bug: 138374585
Test: flash device, run test app
Change-Id: I24f5dc125488c6af3164b6503f236bc3a24e6292
Merged-In: I24f5dc125488c6af3164b6503f236bc3a24e6292