Add extended PaperServerListPingEvent

Add a new event that extends the original ServerListPingEvent
and allows full control of the response sent to the client.

paper-api/src/main/java/org/bukkit/util/CachedServerIcon.java

@@ -18,4 +18,9 @@ public interface CachedServerIcon {
     @Nullable
     public String getData(); // Paper
 
+    // Paper start
+    default boolean isEmpty() {
+        return getData() == null;
+    }
+    // Paper end
 }