Introduce lowlightclock module.

This changelist introduces the lowlightclock module. This module handles
rendering a low light experience based on ambient sensor input.

Fixes: 385340515
Test: atest AmbientLightModeMonitorTest
Test: atest ChargingStatusProviderTest
Test: atest DirectBootConditionTest
Test: atest ForceLowLightConditionTest
Test: atest LowLightClockAnimationProviderTest
Test: atest LowLightClockDreamServiceTest
Test: atest LowLightConditionTest
Test: atest LowLightMonitorTest
Test: atest ScreenSaverEnabledConditionTest
Flag: com.android.systemui.low_light_clock_dream
Change-Id: I6d5bdbb09fa2ec3e6bf78ae4f8725799525c2162