feat(events,example): integrate at example backend

Integrate plugins-events-backend with plugins-events-backend-module-http
at the example backend.

Relates-to: #11082
Signed-off-by: Patrick Jungermann <Patrick.Jungermann@gmail.com>

packages/backend/package.json

@@ -40,6 +40,8 @@
     "@backstage/plugin-badges-backend": "workspace:^",
     "@backstage/plugin-catalog-backend": "workspace:^",
     "@backstage/plugin-code-coverage-backend": "workspace:^",
+    "@backstage/plugin-events-backend": "workspace:^",
+    "@backstage/plugin-events-node": "workspace:^",
     "@backstage/plugin-graphql-backend": "workspace:^",
     "@backstage/plugin-jenkins-backend": "workspace:^",
     "@backstage/plugin-kafka-backend": "workspace:^",