Support for erlkaf built on the official kafka C library

[tpitale]

librdkafka is the official Confluent kafka library (in C). The erlang/elixir library built on top of it is called erlkaf.

These libraries offer support for some features that are not in brod (and don't appear to be planned).

Would it be possible (or would you be open to) switching to an adapter pattern for the underlying kafka, so that we might implement support in elsa for using erlkaf in place of brod?

[tpitale]

I realize that erlkaf is using a NIF, so this would not be ideal for everyone to use. Thus the suggestion of using an adapter library.