feat: Modularize KueModal component by extracting handler functions

- Moved `handleSave`, `handleChange`, `handleDisplayEinschalten`, `handleSetDateTime`, `handleClearDatabase`, and `handleReboot` to separate handler files for better modularity and code organization.
- Updated imports in `KueModal.jsx` and `SettingsModal.jsx` to use new handler files.
- Improved code readability and maintainability by organizing functions into dedicated handler modules.

components/modales/settingsModal/handlers/handleSetDateTime.js

@@ -41,3 +41,5 @@ const handleSetDateTime = () => {
       alert("Fehler beim Setzen von Datum und Uhrzeit!");
     });
 };
+
+export default handleSetDateTime;