Dynamic Client doesn't discover newly created resources after operator has run

[fanminshi]

Currently The SDK's query, action, and Watch APIs are not able to discover a new resource
type after the operator has initiated.

For example:

We have a setup such that the operator gets the AppService resource every 5 seconds:

a := &v1alpha1.AppService{
	TypeMeta: metav1.TypeMeta{
		Kind:       "AppService",
		APIVersion: "example.com/v1alpha1",
	},
	ObjectMeta: metav1.ObjectMeta{
		Name:      "bla",
		Namespace: "default",
	},
}
for {
	err := query.Get(a)
	if err != nil {
		logrus.Error(err)
	}
	time.Sleep(5 * time.Second)
}

Initially, the CRD of AppService is not registered.

$ kubectl get CRD
No resources found.

The above code prints the error:

ERRO[0000] failed to get resource client for (apiVersion:example.com/v1alpha1, kind:AppService, ns:default): failed to get resource type: failed to get the resource REST mapping for GroupVersionKind(example.com/v1alpha1, Kind=AppService): no matches for example.com/, Kind=AppService

Let's create the CRD:

$ kubectl get crd
NAME                      AGE
appservices.example.com   7s

We expect the getter from main loop to eventually discover the AppService resource so that
the getter gets the correct resource. However, that does not happen, and we get the same error as before:

ERRO[0035] failed to get resource client for (apiVersion:example.com/v1alpha1, kind:AppService, ns:default): failed to get resource type: failed to get the resource REST mapping for GroupVersionKind(example.com/v1alpha1, Kind=AppService): no matches for example.com/, Kind=AppService