INTEXT-111 Allow PP for Kafka producer context

 - Remove hard coded names for bean names at the producer context parser
 - Fix and update tests
 - Remove the use of `BeanFactory` to get the producerConfigurations in
KakfaProducerContext and use setter to set the producerConfigurations
 - Add logic to send the message from producer configuration when there
is no header specified for the topic and single producer configuration
is used.
@ilayaperumalg , that's all. It is only single critical concern.
Let me know and I'll fix it on merge.

I'd say that you have an issue with code style though, but I do `artemized` on each merge :smile: