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

tests/robotests/src/com/android/settings/dashboard/DashboardFragmentTest.java

@@ -69,7 +69,7 @@ public class DashboardFragmentTest {
         mDashboardCategory.tiles = new ArrayList<>();
         mDashboardCategory.tiles.add(new Tile());
         mTestFragment = new TestFragment(ShadowApplication.getInstance().getApplicationContext());
-        mTestFragment.onAttach(mContext);
+        mTestFragment.onAttach(ShadowApplication.getInstance().getApplicationContext());
         when(mFakeFeatureFactory.dashboardFeatureProvider.getTilesForCategory(anyString()))
                 .thenReturn(mDashboardCategory);
     }
@@ -126,7 +126,7 @@ public class DashboardFragmentTest {
         }
 
         @Override
-        protected String getPreferenceKey() {
+        public String getPreferenceKey() {
             return null;
         }