clusterctl: Add public function to create new CRD migrator

Signed-off-by: Alexandr Demicev <alexandr.demicev@suse.com>

cmd/clusterctl/client/cluster/crd_migration.go

@@ -42,6 +42,11 @@ type crdMigrator struct {
 	Client client.Client
 }
 
+// NewCRDMigrator public function to create a new CRD migrator.
+func NewCRDMigrator(client client.Client) *crdMigrator { //nolint:revive
+	return newCRDMigrator(client)
+}
+
 // newCRDMigrator creates a new CRD migrator.
 func newCRDMigrator(client client.Client) *crdMigrator {
 	return &crdMigrator{