Add supervisor port

In k3s today the kubernetes API and the /v1-k3s API are combined into
one http server.  In rke2 we are running unmodified, non-embedded Kubernetes
and as such it is preferred to run k8s and the /v1-k3s API on different
ports.  The /v1-k3s API port is called the SupervisorPort in the code.

To support this separation of ports a new shim was added on the client in
then pkg/agent/proxy package that will launch two load balancers instead
of just one load balancer.  One load balancer for 6443 and the other
for 9345 (which is the supervisor port).

pkg/cluster/https.go

@@ -18,7 +18,7 @@ import (
 )
 
 func (c *Cluster) newListener(ctx context.Context) (net.Listener, http.Handler, error) {
-	tcp, err := dynamiclistener.NewTCPListener(c.config.BindAddress, c.config.HTTPSPort)
+	tcp, err := dynamiclistener.NewTCPListener(c.config.BindAddress, c.config.SupervisorPort)
 	if err != nil {
 		return nil, nil, err
 	}