Support proxy-url from host cluster kubeconfig in SetControlplaneConfig for Karmada operator

[qiuming520]

What would you like to be added:
When deploying Karmada instance via karmada.operator.karmada.io/v1alpha1 CR with host cluster kubeconfig that contains proxy-url, make karmada-operator automatically parse and inject the proxy-url field into control plane config when building host cluster connection in SetControlplaneConfig logic, so that operator can properly connect target Karmada control plane and complete the installation of karmada-apiserver and other control plane components successfully.

Locations:

karmada/operator/pkg/tasks/init/upload.go

Lines 117 to 126 in 2f47894

	// store rest config to RunData.
	config, err := clientcmd.RESTConfigFromKubeConfig(configBytes)
	if err != nil {
	return err
	}
	data.SetControlplaneConfig(config)
	klog.V(2).InfoS("[UploadAdminKubeconfig] Successfully created secret of karmada apiserver kubeconfig", "karmada", klog.KObj(data))
	return nil
	}

Why is this needed:
Currently, if the kubeconfig of host cluster configured in Karmada CR uses proxy-url to access cluster apiserver, karmada-operator will ignore the proxy-url field during constructing host cluster connection in SetControlplaneConfig phase. Without supplementing proxy-url into client config, operator cannot establish normal connection to target Karmada control plane, resulting in failure to install karmada-apiserver and other core control plane components, which blocks the whole Karmada instance deployment flow for environments that rely on proxy to access Kubernetes clusters.

Locations:

karmada/operator/pkg/tasks/init/karmadaresource.go

Lines 79 to 96 in 2f47894

	func runSystemNamespace(r workflow.RunData) error {
	data, ok := r.(InitData)
	if !ok {
	return errors.New("systemName task invoked with an invalid data struct")
	}
	err := apiclient.CreateNamespace(data.KarmadaClient(), &corev1.Namespace{
	ObjectMeta: metav1.ObjectMeta{
	Name: constants.KarmadaSystemNamespace,
	},
	})
	if err != nil {
	return fmt.Errorf("failed to create namespace %s, err: %w", constants.KarmadaSystemNamespace, err)
	}
	klog.V(2).InfoS("[systemName] Successfully created karmada system namespace", "namespace", constants.KarmadaSystemNamespace, "karmada", klog.KObj(data))
	return nil
	}

[qiuming520]

/assign