Update BatteryStatsImpl to track per-procstate cpu times.

BatteryStatsImpl will track this data by reading from
/proc/uid/<uid>/time_in_state whenever process state changes
and will include this data as part of batterystats dump.

Bug: 66953194
Test: atest core/tests/coretests/src/com/android/internal/os/BatteryStatsTests.java
Test: atest hostsidetests/incident/src/com/android/server/cts/BatteryStatsValidationTest.java
Test: atest core/tests/coretests/src/com/android/internal/os/BstatsCpuTimesValidationTest.java

Change-Id: Ibb3e07f518aaf7eea2a00bb95b95dc5f7e09552e