Gateway API: set supported version condition on GatewayClass

[skriss]

ref. kubernetes-sigs/gateway-api#2384

[sunjayBhatia]

Todos here:

• add RBAC for and fetch gatewayclasses.gateway.networking.k8s.io CustomResourceDefinition
  • on provisioner startup? or maybe better on each GatewayClass reconcile loop so if the CRDs are changed, we can find that out?
• if resource has gateway.networking.k8s.io/bundle-version annotation value that is not supported, then add status condition SupportedVersion: False with appropriate reason/message (otherwise True)
• make a decision on what versions are supported
  • do we support version skew?
  • if so, need to test multiple versions of the CRDs
  • what happens if CRD bundle version is updated to an unsupported version?