Merge pull request #37561 from deads2k/fed-01-types

Automatic merge from submit-queue (batch tested with PRs 36990, 37494, 38152, 37561, 38136)

api federation types

First commit adds types that can back the kubernetes-discovery server with an `kubectl` compatible way of adding federated servers.  Second commit is just generated code.

After we have types, I'd like to start splitting `kubernetes-discovery` into a "legacy" mode which will support what we have today and a "normal" mode which will provide an API federation server like this: https://github.com/kubernetes/kubernetes/blob/master/docs/proposals/federated-api-servers.md that includes both discovery and proxy in a single server.  Something like this: https://github.com/openshift/kube-aggregator .

@kubernetes/sig-api-machinery @nikhiljindal

test/integration/discoverysummarizer/discoverysummarizer_test.go

@@ -22,7 +22,7 @@ import (
 	"testing"
 	"time"
 
-	"k8s.io/kubernetes/cmd/kubernetes-discovery/discoverysummarizer"
+	"k8s.io/kubernetes/cmd/kubernetes-discovery/pkg/legacy"
 	"k8s.io/kubernetes/examples/apiserver"
 )
 
@@ -50,7 +50,7 @@ func runDiscoverySummarizer(t *testing.T) string {
 	configFilePath := "../../../cmd/kubernetes-discovery/config.json"
 	port := "9090"
 	serverURL := "http://localhost:" + port
-	s, err := discoverysummarizer.NewDiscoverySummarizer(configFilePath)
+	s, err := legacy.NewDiscoverySummarizer(configFilePath)
 	if err != nil {
 		t.Errorf("unexpected error: %v\n", err)
 	}