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>

test/integration/supervisor_secrets_test.go

@@ -21,7 +21,7 @@ import (
 
 func TestSupervisorSecrets(t *testing.T) {
 	env := library.IntegrationEnv(t)
-	kubeClient := library.NewClientset(t)
+	kubeClient := library.NewKubernetesClientset(t)
 	supervisorClient := library.NewSupervisorClientset(t)
 
 	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)