Use BatterySaverReceiver in battery saver settings

Use this receiver to listen to following updates:
1. Plug state: if it is plugged in, disable this two state
button, otherwise make it enabled
2. low power mode: If mode on, show "turn off" otherwise show
"turn on"

Bug: 72228477
Test: RunSettingsRoboTests
Change-Id: Ib3d3df9f9a5fbac8b1b876c9e193beb75f522ebd