Show charging speed in Settings

- Move BatteryStatus from KeyguardUpdateMonitor to SettingsLib
which can be used in Settings and SystemUI
- Add string to support show rapid and slow charging in Settings
- Move config from res-keyguard to SettingsLib

Fixes: 79559900
Fixes: 66573773
Test: manual, make RunSettingsLibRoboTests
Change-Id: I2ffd902743819f999ee3a10bbadc2d3ca45495c2