Adds bool to force non-aggregated discovery

Kubernetes-commit: a84d877310ba5cf9237c8e8e3218229c202d3a1e

discovery/cached/disk/cached_discovery.go

@@ -277,6 +277,12 @@ func (d *CachedDiscoveryClient) Invalidate() {
 	}
 }
 
+// WithLegacy returns current cached discovery client;
+// current client does not support legacy-only discovery.
+func (d *CachedDiscoveryClient) WithLegacy() discovery.DiscoveryInterface {
+	return d
+}
+
 // NewCachedDiscoveryClientForConfig creates a new DiscoveryClient for the given config, and wraps
 // the created client in a CachedDiscoveryClient. The provided configuration is updated with a
 // custom transport that understands cache responses.

discovery/cached/disk/cached_discovery_test.go

@@ -786,6 +786,10 @@ func (d *fakeDiscoveryClient) OpenAPIV3() openapi.Client {
 	panic("unimplemented")
 }
 
+func (d *fakeDiscoveryClient) WithLegacy() discovery.DiscoveryInterface {
+	panic("unimplemented")
+}
+
 func groupNamesFromList(groups *metav1.APIGroupList) []string {
 	result := []string{}
 	for _, group := range groups.Groups {