net/benthos: Add new port

Benthos solves common data engineering tasks such as transformations,
integrations, and multiplexing with declarative and unit testable
configuration. This allows you to easily and incrementally adapt your data
pipelines as requirements change, letting you focus on the more exciting stuff.

Benthos is able to glue a wide range of sources and sinks together and hook
into a variety of databases, caches, HTTP APIs, lambdas and more, enabling you
to seamlessly drop it into your existing infrastructure.