AppScanStats: allow to inject time provider

By injecting an interface that can be used to get the time, we allow
test to fake the time

Bug: 330956986
Fix: 330956986
Bug: 380539632
Bug: 380510617
Bug: 380510672
Bug: 380536618
Bug: 380510672
Bug: 380510672
Bug: 380536573
Bug: 378542424
Bug: 346028665
Bug: 347474468
Test: atest ScanManagerTest --rerun-until-failure 3000
Flag: TEST_ONLY || The change in app are no-op
Change-Id: I82fcae4a1c366249ae96924ae49527e44e004fb4