Adapting k8s.io/apiserver in KubeVirt

KubeVirt extends Kubernetes with virtual machine (VM) APIs, virt-api is the component that serves these APIs to the cluster. Historically, the virt-api component has relied on a custom HTTP server implementation to manually handle TLS, authentication (Authn), authorization (Authz), API discovery, and OpenAPI serving. This VEP proposes migrating virt-api to the k8s.io/apiserver library to leverage the standard Kubernetes API server infrastructure. Adopting this upstream standard will significantly reduce maintenance overhead and enable seamless security updates for the system.