ClusterManagementAddOn and ManagedClusterAddon API v1beta1

[haoqing0110]

open-cluster-management-io/ocm#1218

v1beta1

ClusterManagementAddOn spec.defaultConfigs
ManagedClusterAddon status.registrations
v1alpha1 <-> v1beta1 conversion webhook

ClusterManagementAddOn spec.supportedConfigs (v1alpha1) <-> spec.defaultConfigs (v1beta1)
ManagedClusterAddon spec.installNamespace (v1alpha1) <-> installNamespace (v1beta1)
ManagedClusterAddon status.registrations(v1alpha1) <-> status.registrations (v1beta1)