Support custom IngressControllers for the virt launcher networkPoilcy

Hello, We have started experiencing the deployment of nested clusters in openshift using hypershift. We have tried to deploy a cluster using `openshift virtualization`, and the nodes (VMs) that were created, failed to provision successfully because they weren't able to communicate with the ignition server. After some research, we came to the conclusion that the one responsible for the connectivity issues is the `virt launcher` networkPolicy. To verify it we removed the `hypershift.openshift.io/infra-id` label (which is the label picking the VMs) and the nodes were successfully provisioned. We analyzed the networkPolicy and saw that traffic is allowed only to the `default` ingressController: ``` - podSelector: matchLabels: ingresscontroller.operator.openshift.io/deployment-ingresscontroller: default ``` We do use ingress sharding in our hosting cluster, which means that traffic is forwarded to the `sharded-default` ingressController and not the `default` ingressController Right now, we cannot modify manually the networkPolicy, as the controller just reconciles it back to the original state. I would like to suggest adding a field in the `HostedCluster` resource which allows changing the the name of the ingressController that will be used for the `virt launcher` network policy. Best regards, Or Rener