Kafka Lambda support

[jackburridge]

Add support for a Kafka AMGI Lambda server, in the form of a Lambda handler.

This should expect events in the form of a MSK Kafka event from a MSK event source mapping. This should also work with a self-managed Kafka event as they are almost identical.

Todo

• AMGI Kafka Lambda handler
• Kafka receive though the handler
• Kafka send
• Graceful shutdown