add flag concurrent-statefulset-syncs to kube-controller-manager (#79169)

* add flag `concurrent-statefulset-syncs` to set number of concurrent workers for statefulset controller

* change default value of ConcurrentStatefulSetSyncs from 1 to 5

* 1. fix doc comment of statefulset config types.go
2. add missing deps k8s.io/kubernetes/pkg/controller/statefulset/config

* add missing dep k8s.io/kubernetes/pkg/controller/statefulset/config/v1alpha1

* updated bazel BUILD files

* update kube-controller-manager options testcase

* fix codegen

* fix golint error

* fix testcase

cmd/kube-controller-manager/app/options/statefulsetcontroller.go

@@ -0,0 +1,63 @@
+/*
+Copyright 2019 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.
+*/
+
+package options
+
+import (
+	"fmt"
+
+	"github.com/spf13/pflag"
+
+	statefulsetconfig "k8s.io/kubernetes/pkg/controller/statefulset/config"
+)
+
+// StatefulSetControllerOptions holds the StatefulSetController options.
+type StatefulSetControllerOptions struct {
+	*statefulsetconfig.StatefulSetControllerConfiguration
+}
+
+// AddFlags adds flags related to StatefulSetController for controller manager to the specified FlagSet.
+func (o *StatefulSetControllerOptions) AddFlags(fs *pflag.FlagSet) {
+	if o == nil {
+		return
+	}
+
+	fs.Int32Var(&o.ConcurrentStatefulSetSyncs, "concurrent-statefulset-syncs", o.ConcurrentStatefulSetSyncs, "The number of statefulset objects that are allowed to sync concurrently. Larger number = more responsive statefulsets, but more CPU (and network) load")
+}
+
+// ApplyTo fills up StatefulSetController config with options.
+func (o *StatefulSetControllerOptions) ApplyTo(cfg *statefulsetconfig.StatefulSetControllerConfiguration) error {
+	if o == nil {
+		return nil
+	}
+
+	cfg.ConcurrentStatefulSetSyncs = o.ConcurrentStatefulSetSyncs
+
+	return nil
+}
+
+// Validate checks validation of StatefulSetControllerOptions.
+func (o *StatefulSetControllerOptions) Validate() []error {
+	if o == nil {
+		return nil
+	}
+
+	errs := []error{}
+	if o.ConcurrentStatefulSetSyncs < 1 {
+		errs = append(errs, fmt.Errorf("concurrent-statefulset-syncs must be greater than 0, but got %d", o.ConcurrentStatefulSetSyncs))
+	}
+	return errs
+}