[Languages] Add new information to system language page.

- Add top Intro preference
 - Add footer preference
 - Add sub string to language picker
 - Modify title of app locale pages

Bug: 242182598 Add information to system language page.
Bug: 241600418 [Panlingual] Change strings on App languages
Test: Maunal test
Change-Id: I9bca8911e8e70c97c273294b3c9d1d73d4ea0cb2

src/com/android/settings/localepicker/LocaleDragAndDropAdapter.java

@@ -43,7 +43,6 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
 
-
 class LocaleDragAndDropAdapter
         extends RecyclerView.Adapter<LocaleDragAndDropAdapter.CustomViewHolder> {
 
@@ -154,8 +153,10 @@ class LocaleDragAndDropAdapter
         final LocaleDragCell dragCell = holder.getLocaleDragCell();
         final String label = feedItem.getFullNameNative();
         final String description = feedItem.getFullNameInUiLanguage();
+
         dragCell.setLabelAndDescription(label, description);
         dragCell.setLocalized(feedItem.isTranslated());
+        dragCell.setCurrentDefault(feedItem.getLocale().equals(Locale.getDefault()));
         dragCell.setMiniLabel(mNumberFormatter.format(i + 1));
         dragCell.setShowCheckbox(mRemoveMode);
         dragCell.setShowMiniLabel(!mRemoveMode);