Add the new UI components required for the plugin loading.

src/main/java/org/nwapw/abacus/fx/AbacusController.java

@@ -42,6 +42,10 @@ public class AbacusController {
     private Button inputButton;
     @FXML
     private ComboBox<String> numberImplementationBox;
+    @FXML
+    private ListView enabledPluginView;
+    @FXML
+    private Button reloadButton;
 
     /**
      * The list of history entries, created by the users.