Add progressive disclsoure

- Add a ProgressiveDisclosureMixin that contains all logic for collapse
  preference list when it's too long
- Refactored PreferenceController's updateState to take a preference
  instead of PreferenceScreen, because with progressive disclosure the
  preference can either be in screen or the mixin. DashboardFragment is
  responsible finding the preference before passing it to controller.

Bug: 32255863
Test: RunSettingsRoboTests

Change-Id: I6713abd61c954ce12732902e5b3ca4d4c0b1563e

src/com/android/settings/network/MobilePlanPreferenceController.java

@@ -120,7 +120,7 @@ public class MobilePlanPreferenceController extends PreferenceController impleme
         return isPrefAllowedForUser && isPrefAllowedOnDevice;
     }
     @Override
-    protected String getPreferenceKey() {
+    public String getPreferenceKey() {
         return KEY_MANAGE_MOBILE_PLAN;
     }