Introduce BackgroundProcessLimitPreferenceCtrl

- Create new BackgroundProcessLimitPreferenceController
 - Create controller inside the DashboardFragment
 - Port logic from DevelopmentSettings into the controller

Bug: 34203528
Test: make RunSettingsRoboTests -j40
Change-Id: Ie151f911917ecf9401df8f3daa6f10770b7a571e

src/com/android/settings/development/DevelopmentSettingsDashboardFragment.java

@@ -404,7 +404,7 @@ public class DevelopmentSettingsDashboardFragment extends RestrictedDashboardFra
         controllers.add(new StrictModePreferenceController(context));
         // profile gpu rendering
         controllers.add(new KeepActivitiesPreferenceController(context));
-        // background process limit
+        controllers.add(new BackgroundProcessLimitPreferenceController(context));
         // background check
         controllers.add(new AppsNotRespondingPreferenceController(context));
         controllers.add(new NotificationChannelWarningsPreferenceController(context));