Add CTS tests for the new UsageStats API

Some notable tests are missing due to their inability to be triggered
on non-eng devices from the CTS test:
- Testing configuration events in the event log.
- Testing configurations in the ConfigurationStats aggregate.
- Testing time changes.
- Testing data eviction after the specified length of time.
- Testing long-term aggregation of data.

Bug:17536113
Change-Id: Ibd0d5fcbe80b5e6e5ea9abd06fc246154f0023fb
5 files changed