Lost onInit property when clone a Props

[tutumagi]

Describe the bug
Lost onInit property when clone a Props.

To Reproduce

props := actor.PropsFromFunc(func(ctx actor.Context) {
	switch msg := ctx.Message().(type) {
	case *actor.Started:
		fmt.Printf("Started %v", msg)
	case *shared.Hello:
		fmt.Printf("Hello %v\n", msg.Name)
	}
}, actor.WithOnInit(func(ctx actor.Context) {
	// It does not execute the OnInit callback when spawn a "hello" kind actor.
	fmt.Printf("OnInit %v", ctx)  
}))
helloKind := cluster.NewKind("hello", props)

Expected behavior
It can print OnInit {{xxx}} when spawn a "hello" kind actor.

[tutumagi]

I create a PR for this. #830