Use a brightness sensor to determine the screen's initial brightness

- Create a controller to listen to a brightness sensor when the screen is off
- Estimate the ambient lux based on the sensor reading
- Determine the brightness using the ambient lux estimate
- Specify the sensor and the sensor value to lux mapping in the config

Bug: 193224604
Test: Use the device in a bright room, turn the screen off, go to a dark room, turn the screen on, see that the screen doesn't start as too bright.
Test: atest ScreenOffBrightnessSensorControllerTest
Test: atest DisplayDeviceConfigTest
Change-Id: Ib4c4d9e0d6b385b0d309be6b8c27b71af72d4ecc
Merged-In: Ib4c4d9e0d6b385b0d309be6b8c27b71af72d4ecc