1. update clientset, deepcopy using code-generator

2. add a dummy file tools.go to force "go mod vendor" to see
code-generator as dependencies
3. add a script to update CRD
4. add a README to document CRD updating steps
run go mod tidy
update README

vendor/k8s.io/code-generator/cmd/set-gen/main.go

@@ -0,0 +1,56 @@
+/*
+Copyright 2015 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// set-gen is an example usage of gengo.
+//
+// Structs in the input directories with the below line in their comments will
+// have sets generated for them.
+// // +genset
+//
+// Any builtin type referenced anywhere in the input directories will have a
+// set generated for it.
+package main
+
+import (
+	"os"
+	"path/filepath"
+
+	"k8s.io/code-generator/pkg/util"
+	"k8s.io/gengo/args"
+	"k8s.io/gengo/examples/set-gen/generators"
+
+	"k8s.io/klog"
+)
+
+func main() {
+	klog.InitFlags(nil)
+	arguments := args.Default()
+
+	// Override defaults.
+	arguments.GoHeaderFilePath = filepath.Join(args.DefaultSourceTree(), util.BoilerplatePath())
+	arguments.InputDirs = []string{"k8s.io/kubernetes/pkg/util/sets/types"}
+	arguments.OutputPackagePath = "k8s.io/apimachinery/pkg/util/sets"
+
+	if err := arguments.Execute(
+		generators.NameSystems(),
+		generators.DefaultNameSystem(),
+		generators.Packages,
+	); err != nil {
+		klog.Errorf("Error: %v", err)
+		os.Exit(1)
+	}
+	klog.V(2).Info("Completed successfully.")
+}