Auto brightness configuration UI (1/2)

Add back backlight brightness curve adjustment.

Change-Id: I58408111d6366a281303afb469d78588ae88d275

Fix race condition in backlight adjustment.

When configuring the automatic backlight levels, there's a race
condition in setting the lux and brightness settings as the settings
provider doesn't allow storing multiple settings atomically. When
deleting rows, there's quite a high chance of DisplayPowerController
picking up a state where the lux values already have the lower number of
rows, but the brightness values do not, effectively leading to an
ArrayIndexOutOfBoundsException.

Fix that by
- waiting a second of cool-down time until applying the settings and
- adding a sanity check for the very unlikely case that the delay
  between writing both values is > 1 second

Change-Id: I44e41530fc5334aaefc4ab7d3a90542f78fabe0c
JIRA:CYAN-755

Improve auto-brightness handling

- Add a setting to control the auto-brightness algorithm responsitivity
- Make the algorithm react much faster when the ambient brightness
  increases quickly, e.g. when receiving a call in bright sunlight.

Change-Id: Ic608901c476609dde69cae982228c09567140a83

Re-add auto brightness configuration UI (1/2)

- Add a button into the new brightness dialog that allows opening the
  auto brightness setup
- Enable auto-brightness adjustment (setting for general brighter/darker
  adjustment) and twilight adjustment

Change-Id: I7fd11ddaa112396dcb7508692aacb93bfe3da256