BatteryManager: Add new battery properties from the Health V3 HAL.

This adds two new system APIs, BATTERY_PROPERTY_SERIAL_NUMBER and
BATTERY_PROPERTY_PART_STATUS. Both require BATTERY_STATS permissions.

This also removes an obsolete comment in BatteryProperty.java. This
class is no longer connected to BatteryMonitor, which is an
implementation detail to the default Health HAL.

Bug: 309792384
Test: m
Change-Id: I11dfb6a5f4f6e1b754c7191055836693615a6553