Add --rabbitmq-version flag to kubectl-rabbitmq create

[Zerpet]

Note to reviewers: remember to look at the commits in this PR and consider if they can be squashed

Summary Of Changes

Rescued this bit of functionality from #2147

• Added --rabbitmq-version (and -v shorthand) flag to the kubectl-rabbitmq create command.
• If --rabbitmq-version is provided, the rabbitmq.com/version annotation is set on the RabbitmqCluster.
• If --image is not provided, the image is automatically templated as rabbitmq:<version>-management.
• Added unit tests to verify the new flag's behavior with and without the --image flag.

Additional Context

This feature allows users to easily specify the RabbitMQ version when creating a cluster using the CLI, automatically setting the correct annotation and image unless an image is explicitly overridden.

Local Testing

Unit tests passing locally.