Update top of modes page

* Show blurb based on mode type.
* Make the icon bigger and highlight it when mode is active.
* Increase spacing between elements.

Also eliminate some code duplication between header of mode page and header of icon picker.

Fixes: 355415875
Test: manual
Flag: android.app.modes_ui
Change-Id: I7e788b9b5920cedb791d1571b19b37e65ece6d0b

src/com/android/settings/notification/modes/ZenModeFragment.java

@@ -51,6 +51,7 @@ public class ZenModeFragment extends ZenModeFragmentBase {
     protected List<AbstractPreferenceController> createPreferenceControllers(Context context) {
         List<AbstractPreferenceController> prefControllers = new ArrayList<>();
         prefControllers.add(new ZenModeHeaderController(context, "header", this));
+        prefControllers.add(new ZenModeBlurbPreferenceController(context, "mode_blurb"));
         prefControllers.add(
                 new ZenModeButtonPreferenceController(context, "activate", this, mBackend));
         prefControllers.add(new ZenModePreferenceCategoryController(context, "modes_filters"));