Add power management settings into Settings->Battery

The items been added to group are: Adaptive brightness, Sleep.
Battery saver has been moved into this group as well.

Also refactor the code a little bit to make it fit the
preferenceController. Whole refactor of PowerUsageSummary and
PowerUsageDetail will be tracked in b/34386721

Bug: 34279051
Test: runSettingsRoboTests & Screenshot
Change-Id: I702d8479d1b80f7e9cf1a46752c75bf5d189e0f6

src/com/android/settings/fuelgauge/PowerUsageBase.java

@@ -32,12 +32,12 @@ import android.view.MenuItem;
 
 import com.android.internal.os.BatteryStatsHelper;
 import com.android.settings.R;
-import com.android.settings.SettingsPreferenceFragment;
+import com.android.settings.dashboard.DashboardFragment;
 
 /**
  * Common base class for things that need to show the battery usage graph.
  */
-public abstract class PowerUsageBase extends SettingsPreferenceFragment {
+public abstract class PowerUsageBase extends DashboardFragment {
 
     // +1 to allow ordering for PowerUsageSummary.
     @VisibleForTesting