BrightnessTracker should accomodate multiple ambient sensors

Refactor BrightnessTracker so that it receives an array of lux readings rather than listening to the light sensor

Bug: 215100807
Test: atest BrightnessTrackerTest
Test: atest AutomaticBrightnessControllerTest
Change-Id: I9807ecb39ac8962d2dae9e53c68e6eadbba5c50f
Merged-In: I9807ecb39ac8962d2dae9e53c68e6eadbba5c50f