Support for Gateway API metrics

[mrueg]

What would you like to be added: Expose metrics for objects that are part of the Gateway API https://gateway-api.sigs.k8s.io/implementations/v1.1/ Why is this needed:

To see what objects are in the data path for the new way of doing ingress.

Describe the solution you'd like

• Use Custom Resource State Definition similar to HPA or
• Implement them as native resources in Kubernetes.

Additional context

[dgrisonnet]

/triage accepted