Non Operator managed RabbitMQ and Scope across multiple namespaces

[vterdunov]

Hi, thanks for the operators.

I have AWS Managed RabbitMQ and I want to allow my k8s cluster tenants create RabbitMQ objects using Topology Operator.
To manage external RabbitMQ I have to specify spec.rabbitmqClusterReference.connectionSecret.name in a RMQ Custom Resource. By default, the Custom Resources allowed only from the Topology Operator namespace. But, I want to allow tenants to create RMQ CustomResources in their own namespaces. In normal way I can annotate RabbitmqCluster CR with rabbitmq.com/topology-allowed-namespaces. But in my case I don't have the RabbitmqCluster CR.