Setting the Rdkafka logger

[Greg-Myers-SB]

The Racecar config passes the producer variable through https://github.com/zendesk/racecar/blob/097eb354a49d72157c3129cfbadd52ddf60ad91f/lib/racecar/config.rb#L275 to Rdkafka::Config.new https://github.com/zendesk/racecar/blob/097eb354a49d72157c3129cfbadd52ddf60ad91f/lib/racecar/producer.rb#L45 and that is where the Rdkafka logger is set.

Unfortunately producer is a kind of KingConf which only allows simple values and not logger which was stated in #71 and #72 . Is there a correct way to set the Rdkafka::Config.logger such that it is reliably set each time one is initialized?