Break out battery history reading into a separate class

This class will be used by BatteryUsageStats

Bug: 180765532
Test: atest FrameworksCoreTests:com.android.internal.os.BatteryStatsHistoryTest
Test: atest FrameworksCoreTests:com.android.internal.os.BatteryStatsNoteTest
Test: atest FrameworksCoreTests:com.android.internal.os.BatteryStatsHistoryIteratorTest

Change-Id: Ic392bcdb6eb815afcc3cd882aa32dd4c78b6484f
5 files changed