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

- this commit adds as well the complete auto brightness ehancements we had
  on 4.3

Change-Id: I7fd11ddaa112396dcb7508692aacb93bfe3da256