feat(adminmonitor): redirect to timeout page if admin is not created in 5 mins [EE-2691] (#6688)

This PR solves the issue that the Portainer instance will be always accessible in certain cases, like `restart: always` setting with docker run, even if the administrator is not created in the first 5 minutes. 
The solution is that the user will be redirected to a timeout page when any actions, such as refresh the page and click button, are made after administrator initialisation window(5 minutes) timeout.

webpack/webpack.common.js

@@ -108,6 +108,14 @@ module.exports = {
       },
       manifest: './assets/ico/manifest.json',
     }),
+    new HtmlWebpackPlugin({
+      template: './app/timeout.ejs',
+      filename: 'timeout.html',
+      templateParameters: {
+        name: pkg.name,
+        author: pkg.author,
+      },
+    }),
     new WebpackBuildNotifierPlugin({
       title: 'Portainer build',
       logo: path.resolve('./assets/favicon-32x32.png'),