[battery] new more specific view models

Instead of a single view model that describes the state needed for all
use cases (lock screen, home status bar, shade), this CL breaks out the
different behaviors into separate view models that are named by their
behavior.

When utilizing a UnifiedBattery, you can now chose between 3 concrete
view model behaviors that show percentage either when charging, based on
the setting, or always.

Test: BatteryViewModelAlwaysShowPercentTest
Test: BatteryViewModelBasedOnSettingTest
Test: BatteryViewModelShowWhenChargingTest
Test: manual via `adb shell cmd battery`
Bug: 406773990
Flag: com.android.settingslib.flags.new_status_bar_icons
Flag: com.android.systemui.status_bar_root_modernization
Change-Id: I212b07940ffc1e92d228b176f394549d58b08ad0