feat: simplify API udpate signals

dzgui/controllers/emitter.py

@@ -145,6 +145,10 @@ class Emitter(GObject.GObject):
     def api_change_failed(self) -> None:
         pass
 
+    @GObject.Signal(flags=GObject.SignalFlags.RUN_LAST, arg_types=())
+    def api_change_successful(self) -> None:
+        pass
+
     @GObject.Signal(flags=GObject.SignalFlags.RUN_LAST, arg_types=())
     def already_saved_server(self) -> None:
         pass