Export BatteryStats info to Atrace.

This is a tm-qpr re-write of http://ag/19779936 and http://ag/19806033. There was large refactor of BatteryStatsHistory that prevent the changes from being cherry-picked directly. Instead, this change copies the relevant sections and stitches together the rest.

Things that are identical
* The whole TraceDelegate
* recordTraceCounters
* recordTraceEvents

Things that are different
* Record calls are moved to BatteryStatsImpl
* Class setup (mTracer isn't changeable)
* No tests (can be added, but hard prior to the refactor)

Bug: 245749764
Test: presubmit and local perfetto tracing
Merged-In: Iaae4e9796a44be3ffdaee31b956bbb3e87735ead
Change-Id: I62fc2e93b662b89176cc26bdff8b3e88d216028a