DLQ support

[RashmiRam]

We use http output plugin to push the events to our own java service and we wanted to retry at later time/push failed events to separate outputs in case of 404 or 401 or 403 from our java service. But, currently there is no way to capture the failed events.

I see that DLQ is already supported in elasticsearch output plugin. I suppose DLQ support in http output is also possible without major changes. I am more than happy to raise a PR for the same if we decide to include the support for DLQ

[andsel]

Hi @RashmiRam the desire is to use DLQ in more output other than Elasticsearch output. So if you want to contribute with a PR to the output http would be awesome.