Common interface for SetControllerReference

[Adirio]

Is there any reason not to combine metav1.Object and runtime.Object into a single MetaV1RuntimeObject interface?

type MetaV1RuntimeObject interface {
	metav1.Object
	runtime.Object
}

SetControllerReference is casting a metav1.Object into a runtime.Object which means that if this fails it will fail at run time instead of compile time.

https://github.com/kubernetes-sigs/controller-runtime/blob/master/pkg/controller/controllerutil/controllerutil.go#L57-L89

func SetControllerReference(owner, object metav1.Object, scheme *runtime.Scheme) error {
	ro, ok := owner.(runtime.Object)
	if !ok {
		return fmt.Errorf("%T is not a runtime.Object, cannot call SetControllerReference", owner)
	}

	// ...
}

would be turned into

func SetControllerReference(owner MetaV1RuntimeObject, object metav1.Object, scheme *runtime.Scheme) error {
	// ...
}

[alexeldeib]

#594