Cluster-scoped resources are not deleted when deleting namespaced scoped Gateway

[michaelvl]

Controller references are used between parent and child resources, which only works for namespace scoped resources.

The pattern for solving this could follow how claims vs. actual resource is handled for e.g. volumes (namespaced claim maps to cluster-scoped resource). Potentially a 'master' cluster scoped resource could be used as an owner for all templated resources.

Random thought: Maybe the claim thinking can be generalized to implement shared gateways and migration usecases. I.e. multiple 'gateway claims' are fulfilled by a specific cluster-scoped 'master' gateway that also serves as owner for templated resources.