samsung: doze: Re-integrate into Settings

samsung: doze: Re-integrate into Settings

* Apply the default Oreo theme and inherit the layouts
  from Google for the Settings app, in order to keep
  UI consistency.

* Get rid of SettingsDrawerActivity as it no longer fits in
  and include the back button in the action bar.

* Kill the icon drawable not only because is a leftover,
  but also doesn't really serve any puropose in the new UI.

Change-Id: I71ea2c118dcfd387904d04516572902babb16e35