Allow the creation of global consumers across control planes

Currently in Konnect consumers need to be created in each control plane where needed - even if its the same consumer.

I have a customer who have a setup where the same consumer is created in multiple control planes (with the same id). In Konnect we treat these as separate consumers when it comes to Analytics - however for this customer - they treat this as the same consumer just having access to APIs in multiple control planes.

What would be great is the concept of global consumers where we could assign them rights to specific APIs (gateway services) regardless of which control plane they reside in.