refactor: Improve typings for element-ui imports (no-changelog) (#4678)

* convert all stories to typescript

* stricter typing for element-ui imports

packages/design-system/.storybook/preview.js

@@ -1,11 +1,17 @@
 import './font-awesome-icons';
 import './storybook.scss';
 
+import ElementUI from 'element-ui';
 import lang from 'element-ui/lib/locale/lang/en';
 import locale from 'element-ui/lib/locale';
 
+import designSystemComponents from '../src/plugins/n8nComponents';
+
 import Vue from 'vue';
 
+Vue.use(ElementUI);
+Vue.use(designSystemComponents);
+
 locale.use(lang);
 
 // https://github.com/storybookjs/storybook/issues/6153