Use ambient light sensor to adjust camera privacy light brightness

If there is a light sensor available at boot then we will watch for
changing values and compute the integral of the values over the past
specified interval. Light sensor values are transformed with a logorithm
since it was observed that values increase very quickly with addition of
artificial light although as a human it feels that brightness is
increasing linearly (some light research tells this is called
Fechner's law)

Bug: 216107392
Test: CameraPrivacyLightControlllerTest

Change-Id: I94742d099d6a5d074173a21e629a3044f0a10c9a