add collection resource client

[calvin0327]

Signed-off-by: calvin wen.chen@daocloud.io

fixed: #37

/kind feature

add client to satisfy clusterpedia collectionresource feature.

[calvin0327]

@Iceber @ClerverHu /cc

[cleverhu]

/lgtm

[Iceber]

It looks like the custom resource client and collection can be combined into ClusterPediaV1alpha1Client
eg.

type ClusterPediaV1beta1 interface {
        ListCollectionResources() (*clusterpediav1beta1.CollectionResourceList, error)
        CollectionResource(name string) CollectionResourceInterface

        Resource(resource schema.GroupVersionResource) NamespaceableResourceInterface
}

type CollectionResourceInterface interface {
        Fetch(ctx context.Context, opts metav1.ListOptions, params map[string]string) (*clusterpediav1beta1.CollectionResource, error)
}

type ResourceInterface interface {
        List(ctx context.Context, opts metav1.ListOptions, params map[string]string, obj runtime.Object) error
}

type NamespaceableResourceInterface interface {
        Namespace(string) ResourceInterface
        ResourceInterface
}

What do you think?