Summary

As a user of ClusterLogForwarder,
I want to define custom request headers
So I can use an Elasticsearch output to forward to VictoriaLogs

Acceptance Criteria

• Verify custom header's are added to the request when spec'd for an Elasticsearch output
• Verify the upstream API documentation is regenerated

Notes & Questions

1. What are the implications when using a bearer token auth? Do we need to restrict certain header keys or values?