[ENHANCEMENT] Add support for namespaces: Self after the removal of sameLabels

[jsalatiel]

Maybe I am missing something, but now that sameLabels was removed, I dont see how I would create a AdminNeworkPolicy that would allow all pods with role=frontend to talk to pods with role=backend as long as they are in the same namespace. Reading the docs, that wold be possible by setting the same labels to match kubernetes.io/metadata.name, but now that's not possible anymore.

I see other CNI implementations, like vmware antrea for example, has a namespaces: Self that does exactly that.
Maybe implement something like that would work for this use case.