feat: improve config UI (#69)

* add first concept

* completed configuration ui update

* add button for testing email configuration

* improve mobile layout

* add migration

* run formatter

* delete unnecessary modal

* remove unused comment

frontend/src/pages/admin/config.tsx

@@ -1,5 +1,5 @@
 import { Space, Title } from "@mantine/core";
-import AdminConfigTable from "../../components/admin/AdminConfigTable";
+import AdminConfigTable from "../../components/admin/configuration/AdminConfigTable";
 
 const AdminConfig = () => {
   return (