Add RabbitMQ functionality

Add support for user tags and permissions to the rabbitmq_user state,
which requires adding support for set_user_tags to the rabbitmq module.

Also add a rabbitmq_plugin state, which requires adding rabbitmq-plugin
support to the rabbitmq module.
Merge pull request #7683 from jesusaurus/feature/rabbitmq

Add more RabbitMQ functionality
Fix PEP-8 E302. Add UTF-8 header.
Fix PEP-8 E302. Add UTF-8 header.
Fix PyLint W0102. Dangerous default value.
Fix PEP-8 E302.