Work out how to add multiple domains for OpenAerialMap API deployment

[spwoodcock]

• This was solved upstream: Pass an array of hosts for the Ingress developmentseed/eoapi-k8s#248
• We can now support an array of domains for the ingress.
• We need to work out how to use multiple domains for the external-dns and letsencrypt config, if possible.
• Ideally we can deploy the same server under two TLS endpoints:
  • api.imagery.hotosm.org --> user facing
  • oam-eoapi-prod.imagery-services.k8s-prod.hotosm.org --> internal facing reference

[spwoodcock]

Sure this is nice to have, but do we really need an external and internal domain, both managed by k8s?

Worst case we could handle this all manually via DNS...