Merge pull request #57504 from yue9944882/fix-fake-client-dummy-watch

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

feat(fakeclient): push event on watched channel on add/update/delete

**What this PR does / why we need it**:

This PR enables watch function for kubernetes [fakeclient](1bcf0b0a22/staging/src/k8s.io/client-go/kubernetes/fake/clientset_generated.go (L88)). 

This fake client add watchReactorFunction by wrapping [watch.NewFake](1bcf0b0a22/staging/src/k8s.io/client-go/kubernetes/fake/clientset_generated.go (L98)) which is a `chan Event` but actually nothing pushes objects into this channel. So all watch function called by fake client will never return or never receive any object. 

This PR intercepts ReactionFunc of `Create / Update / DeleteActionImpl` and will push the requested object to channel. 

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):

Fixes #54075

**Special notes for your reviewer**:

**Release note**:

```dev-release-note
enable watch function for fake client
```

pkg/client/clientset_generated/internalclientset/fake/clientset_generated.go

@@ -71,7 +71,15 @@ func NewSimpleClientset(objects ...runtime.Object) *Clientset {
 
 	fakePtr := testing.Fake{}
 	fakePtr.AddReactor("*", "*", testing.ObjectReaction(o))
-	fakePtr.AddWatchReactor("*", testing.DefaultWatchReactor(watch.NewFake(), nil))
+	fakePtr.AddWatchReactor("*", func(action testing.Action) (handled bool, ret watch.Interface, err error) {
+		gvr := action.GetResource()
+		ns := action.GetNamespace()
+		watch, err := o.Watch(gvr, ns)
+		if err != nil {
+			return false, nil, err
+		}
+		return true, watch, nil
+	})
 
 	return &Clientset{fakePtr, &fakediscovery.FakeDiscovery{Fake: &fakePtr}}
 }