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/import-boss/main.go

@@ -0,0 +1,96 @@
+/*
+Copyright 2016 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.
+*/
+
+// import-boss enforces import restrictions in a given repository.
+//
+// When a directory is verified, import-boss looks for a file called
+// ".import-restrictions". If this file is not found, parent directories will be
+// recursively searched.
+//
+// If an ".import-restrictions" file is found, then all imports of the package
+// are checked against each "rule" in the file. A rule consists of three parts:
+//
+// - A SelectorRegexp, to select the import paths that the rule applies to.
+//
+// - A list of AllowedPrefixes
+//
+// - A list of ForbiddenPrefixes
+//
+// An import is allowed if it matches at least one allowed prefix and does not
+// match any forbidden prefix. An example file looks like this:
+//
+// {
+//   "Rules": [
+//     {
+//       "SelectorRegexp": "k8s[.]io",
+//       "AllowedPrefixes": [
+//         "k8s.io/gengo/examples",
+//         "k8s.io/kubernetes/third_party"
+//       ],
+//       "ForbiddenPrefixes": [
+//         "k8s.io/kubernetes/pkg/third_party/deprecated"
+//       ]
+//     },
+//     {
+//       "SelectorRegexp": "^unsafe$",
+//       "AllowedPrefixes": [
+//       ],
+//       "ForbiddenPrefixes": [
+//         ""
+//       ]
+//     }
+//   ]
+// }
+//
+// Note the second block explicitly matches the unsafe package, and forbids it
+// ("" is a prefix of everything).
+package main
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/spf13/pflag"
+	"k8s.io/code-generator/pkg/util"
+	"k8s.io/gengo/args"
+	"k8s.io/gengo/examples/import-boss/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/...",
+		"k8s.io/kubernetes/cmd/...",
+		"k8s.io/kubernetes/plugin/...",
+	}
+	pflag.CommandLine.BoolVar(&arguments.IncludeTestFiles, "include-test-files", false, "If true, include *_test.go files.")
+
+	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.")
+}