Add method to get blocked app count

So we can sure it in settings

Test: runtest systemui-notification
Bug: 73018368
Change-Id: Ib0185e97f8e1cec1864ca1e4efb23bf8db097901
diff --git a/core/java/android/app/INotificationManager.aidl b/core/java/android/app/INotificationManager.aidl
index 5461c0c..0f2a11a 100644
--- a/core/java/android/app/INotificationManager.aidl
+++ b/core/java/android/app/INotificationManager.aidl
@@ -86,6 +86,7 @@
     ParceledListSlice getNotificationChannelGroups(String pkg);
     boolean onlyHasDefaultChannel(String pkg, int uid);
     ParceledListSlice getRecentNotifyingAppsForUser(int userId);
+    int getBlockedAppCount(int userId);
 
     // TODO: Remove this when callers have been migrated to the equivalent
     // INotificationListener method.