Provide BatteryControllerImpl

- move the initialization methods out of the constructor and into an init method
- @Provides that ensures the init method gets called

Bug: 155685169
Test: atest SystemUITests:BatteryControllerTest
Merged-In: I064442fcf56397ba6394ee98ccf9cc82e589a0e3
Change-Id: Ifd7a3e41714b488ed7144f2344f7488184d48951