Switch brightnessmapper within ABC

Switch which brightness mapping strategy is used in
automaticbrightnesscontroller based on calls from displaypowercontroller
through ABC.
Don't notify of brightness changes in idle mode.

Bug: 205686215
Test: adb shell dumpsys display | grep -A10 Idle
Test: atest BrightnessMappingStrategyTest
AutomaticBrightnessControllerTest
adb shell dumpsys DockObserver set state [0|3]

Change-Id: I8babe42957bfa4939cc78a9763c7fca3c244b73b