Introduce PowerStatsInternal and replace PowerStatsHalWrapper usage

PowerStatsService will handle PowerStatsHal queries, PowerStatsInternal
will provide the LocalService for querying PowerStatsHal derived data
from other System services.

Bug: 173077356
Test: atest FrameworksCoreTests:com.android.internal.power.MeasuredEnergyStatsTest
Test: atest com.android.server.powerstats.PowerStatsServiceTest

Change-Id: Ibc0165a44ffdbbcc9328c250f1dca3d29616c766