feat: notify sentry when connection test on new host fail

app/components/switch_domain_banner_component/switch_domain_banner_component.html.haml

@@ -5,7 +5,9 @@
     fetch(hintUrl, { mode: 'cors' }).then(() => {
       window.location = '#{new_host_url}';
     }).catch((e) => {
-      // TODO: notify us in order to monitor connectivity issues volume
+      const error = new Error("Connection test on new host failed: " + e);
+      const event = new CustomEvent("sentry:capture-exception", { detail: error });
+      setTimeout(() => dispatchEvent(event), 100); // listener is not immediately enabled
     })