Add vanish compatibility

Author: Jakubk15

chatformatter-core/src/main/java/com/eternalcode/formatter/mention/controller/MentionSuggestionsController.java

@@ -28,6 +28,10 @@ private void updateChatSuggestions() {
         List<String> completions = new ArrayList<>();
 
         for (Player player : allPlayers) {
+            if (player.isInvisible()) { // Vanish compatibility
+                continue;
+            }
+
             String s = "@" + player.getName();
             completions.add(s);
         }