Default setup for excessive I/O notification

- Set sample default values for the thresholds that trigger
the I/O notification;
- Centralize tracking of the service's configuration;
- Implement a default broadcast agent.

Test: bit CarServiceTest:com.android.car.CarStorageMonitoringTest
Change-Id: I9eb0259eedd34a27532cb621383b87075c6460a3
8 files changed