Refactor BaseInfo struct

Create another struct that contains the vector of BaseInfos,
currentState key, and hasCurrentState. Now there is a single
currentState key and hasCurrentState per HashableDimensionKey.

Bug: 165817484
Test: `m statsd`
Test: `m statsd_test`
Test: `m`
Test: `atest statsd_test`
Change-Id: I3a541b255829e44d16cfcbe3f2ad14648b759224
3 files changed