Allow multiple Pinnipeds to work on same cluster

Yes, this is a huge commit.

The middleware allows you to customize the API groups of all of the
*.pinniped.dev API groups.

Some notes about other small things in this commit:
- We removed the internal/client package in favor of pkg/conciergeclient. The
  two packages do basically the same thing. I don't think we use the former
  anymore.
- We re-enabled cluster-scoped owner assertions in the integration tests.
  This code was added in internal/ownerref. See a0546942 for when this
  assertion was removed.
- Note: the middlware code is in charge of restoring the GV of a request object,
  so we should never need to write mutations that do that.
- We updated the supervisor secret generation to no longer manually set an owner
  reference to the deployment since the middleware code now does this. I think we
  still need some way to make an initial event for the secret generator
  controller, which involves knowing the namespace and the name of the generated
  secret, so I still wired the deployment through. We could use a namespace/name
  tuple here, but I was lazy.

Signed-off-by: Andrew Keesler <akeesler@vmware.com>
Co-authored-by: Ryan Richard <richardry@vmware.com>

cmd/pinniped-supervisor/main.go

@@ -37,6 +37,7 @@ import (
 	"go.pinniped.dev/internal/controllerlib"
 	"go.pinniped.dev/internal/deploymentref"
 	"go.pinniped.dev/internal/downward"
+	"go.pinniped.dev/internal/groupsuffix"
 	"go.pinniped.dev/internal/kubeclient"
 	"go.pinniped.dev/internal/oidc/jwks"
 	"go.pinniped.dev/internal/oidc/provider"
@@ -258,14 +259,15 @@ func run(podInfo *downward.PodInfo, cfg *supervisor.Config) error {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 
-	// TODO remove code that relies on supervisorDeployment directly
 	dref, supervisorDeployment, err := deploymentref.New(podInfo)
 	if err != nil {
 		return fmt.Errorf("cannot create deployment ref: %w", err)
 	}
 
-	_ = *cfg.APIGroupSuffix // TODO: wire API group into kubeclient.
-	client, err := kubeclient.New(dref)
+	client, err := kubeclient.New(
+		dref,
+		kubeclient.WithMiddleware(groupsuffix.New(*cfg.APIGroupSuffix)),
+	)
 	if err != nil {
 		return fmt.Errorf("cannot create k8s client: %w", err)
 	}