Expose some internal types/funcs in envtest

This exposes a few pieces of the new APIs in internal/testing as public
in envtest.  These types are effectively part of public APIs (they're
referenced by public methods or fields of APIServer, ControlPlane, etc),
so we should let users name them.

pkg/envtest/server.go

@@ -57,20 +57,49 @@ const (
 	defaultKubebuilderControlPlaneStopTimeout  = 20 * time.Second
 )
 
-// ControlPlane is the re-exported ControlPlane type from the internal integration package
-type ControlPlane = controlplane.ControlPlane
+// internal types we expose as part of our public API
 
-// APIServer is the re-exported APIServer type from the internal integration package
-type APIServer = controlplane.APIServer
+type (
+	// ControlPlane is the re-exported ControlPlane type from the internal integration package
+	ControlPlane = controlplane.ControlPlane
 
-// Etcd is the re-exported Etcd type from the internal integration package
-type Etcd = controlplane.Etcd
+	// APIServer is the re-exported APIServer 	from the internal integration package
+	APIServer = controlplane.APIServer
 
-// User represents a Kubernetes user to provision for auth purposes.
-type User = controlplane.User
+	// Etcd is the re-exported Etcd 	from the internal integration package
+	Etcd = controlplane.Etcd
 
-// AuthenticatedUser represets a Kubernetes user that's been provisioned.
-type AuthenticatedUser = controlplane.AuthenticatedUser
+	// User represents a Kubernetes user to provision for auth purposes.
+	User = controlplane.User
+
+	// AuthenticatedUser represets a Kubernetes user that's been provisioned.
+	AuthenticatedUser = controlplane.AuthenticatedUser
+
+	// ListenAddr indicates the address and port that the API server should listen on.
+	ListenAddr = process.ListenAddr
+
+	// SecureServing contains details describing how the API server should serve
+	// its secure endpoint.
+	SecureServing = controlplane.SecureServing
+
+	// Authn is an authentication method that can be used with the control plane to
+	// provision users.
+	Authn = controlplane.Authn
+
+	// Arguments allows configuring a process's flags.
+	Arguments = process.Arguments
+
+	// Arg is a single flag with one or more values.
+	Arg = process.Arg
+)
+
+var (
+	// EmptyArguments constructs a new set of flags with nothing set.
+	//
+	// This is mostly useful for testing helper methods -- you'll want to call
+	// Configure on the APIServer (or etcd) to configure their arguments.
+	EmptyArguments = process.EmptyArguments()
+)
 
 // Environment creates a Kubernetes test environment that will start / stop the Kubernetes control plane and
 // install extension APIs

pkg/internal/testing/controlplane/apiserver.go

@@ -15,8 +15,6 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/internal/testing/process"
 )
 
-// TODO: listenaddr needs to be exposes publically so we can set insecureserving
-
 const (
 	// saKeyFile is the name of the service account signing private key file
 	saKeyFile = "sa-signer.key"