Add tracing to franz-go

[yianni]

Hello,

We have developed a plugin[1] for franz-go that adds tracing to Kafka records and exports them to OpenTelemetry. This plugin allows tracing context propagation from upstream input into Kafka records and from Kafka records to downstream output.

We are interested in knowing if the Benthos team would like to incorporate this capability into the project. We can contribute to this feature and would be happy to work with the team. Please let us know your thoughts on this.

[1] https://github.com/twmb/franz-go/pull/294