Create ENV variables for RabbitMQ

[cecoates]

It would be helpful to set RabbitMQ variables similar to how you can set Redis variables:

-e SYMFONY__ENV__REDIS_SCHEME=... (defaults to "tcp", protocol to use to communicate with the target server (tcp, unix, or http))
-e SYMFONY__ENV__REDIS_HOST=... (defaults to "redis", IP or hostname of the target server)
-e SYMFONY__ENV__REDIS_PORT=... (defaults to "6379", port of the target host)
-e SYMFONY__ENV__REDIS_PATH=...(defaults to "~", path of the unix socket file)
-e SYMFONY__ENV__REDIS_PASSWORD=... (defaults to "~", this is the password defined in the Redis server configuration)

It may be due to my inexperience, but I'm not able to edit/update Wallabag's parameters.yml to point to the correct RabbitMQ host and port. Even if I use sed to replace/update text from the parameters.yml within the container itself and bin/console cache:clear -e=prod it always resets to the defaults.