Based on our experiences today with GKE, it will be easier for our users
to configure Ingress health checks if the healthz endpoint is available
on the same public port as the OIDC endpoints.
Also add an integration test for the healthz endpoint now that it is
public.
Also add the optional `containers[].ports.containerPort` to the
supervisor Deployment because the GKE docs say that GKE will look
at that field while inferring how to invoke the health endpoint. See
https://cloud.google.com/kubernetes-engine/docs/concepts/ingress#def_inf_hc
- New optional ytt value called `into_namespace` means install into that
preexisting namespace rather than creating a new namespace for each app
- Also ensure that every resource that is created statically by our yaml
at install-time by either app is labeled consistently
- Also support adding custom labels to all of those resources from a
new ytt value called `custom_labels`
- Tiltfile and prepare-for-integration-tests.sh both specify the
NodePort Service using `--data-value-yaml 'service_nodeport_port=31234'`
- Also rename the namespaces used by the Concierge and Supervisor apps
during integration tests running locally
