Launch RabbitMQ in docker using tmp-proc.

Demos how to use tmp-proc to run RabbitMQ in docker in a unittest.

tmp-proc-rabbitmq

tmp-proc-rabbitmq provides an example of using tmp-proc to launch dockerized RabbitMQ in integration tests.

It provides an instance of Proc for launching the RabbitMQ image, and also provides an instance of Conn that simplifies opening connections to the launched RabbitMQ service from tests that use tmp-proc.