Extract the not-strictly-modes-related parts of ZenModesBackend

So that when it's moved to SettingsLib, it doesn't need to carry that baggage.

Bug: 346519570
Test: atest com.android.settings.notification.modes
Flag: android.app.modes_ui
Change-Id: I7911a521d96f5dbac2c2395171d324b7b54b8b07

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

@@ -60,9 +60,9 @@ import java.util.function.Predicate;
 class ZenModeSummaryHelper {
 
     private final Context mContext;
-    private final ZenModesBackend mBackend;
+    private final ZenHelperBackend mBackend;
 
-    public ZenModeSummaryHelper(Context context, ZenModesBackend backend) {
+    ZenModeSummaryHelper(Context context, ZenHelperBackend backend) {
         mContext = context;
         mBackend = backend;
     }