Use k8s.io/cli-runtime for kubernetes flags

Signed-off-by: Jakob Schrettenbrunner <jakob.schrettenbrunner@telekom.de>

cmd/flux/tree_kustomization.go

@@ -77,14 +77,14 @@ func treeKsCmdRun(cmd *cobra.Command, args []string) error {
 	ctx, cancel := context.WithTimeout(context.Background(), rootArgs.timeout)
 	defer cancel()
 
-	kubeClient, err := utils.KubeClient(rootArgs.kubeconfig, rootArgs.kubecontext)
+	kubeClient, err := utils.KubeClient(kubeconfigArgs)
 	if err != nil {
 		return err
 	}
 
 	k := &kustomizev1.Kustomization{}
 	err = kubeClient.Get(ctx, client.ObjectKey{
-		Namespace: rootArgs.namespace,
+		Namespace: *kubeconfigArgs.Namespace,
 		Name:      name,
 	}, k)
 	if err != nil {