Added RabbitMQ 4 commodity

[leighlbr]

• What kind of change does this PR introduce (Bug fix, feature, docs update, ...)?
  Feature

• What is the current behavior?
  RabbitMQ 3 is supported as a commodity, however RabbitMQ 4 is not

• What is the new behavior (if this is a feature change)?
  RabbitMQ 4 is available as a commodity.

• Does this PR introduce a breaking change? If so, what actions will users need to take in order to regain compatibility?
  No

Checklists

All submissions

• Have you followed the guidelines in our Contributing document?
• Is this PR targeting the develop branch, and the branch rebased with commits squashed if needed?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

New feature and bug fix submissions

• Has your submission been tested locally?
• Has documentation such as the README been updated if necessary?
• Have you linted your new code (using rubocop and markdownlint), and are not introducing any new offenses?

[leighlbr]

There are some breaking changes between RabbitMQ 3 and 4; see https://www.rabbitmq.com/docs/whats-new - hence adding it as a new commodity.

[sichapman]

No need for 2.0/3.7 compose fragments as next devenv version will not support them