add Gateway API support via httpRoute

[minrk]

example, migrate

ingress:
  enabled: true
  hosts:
    - staging.mybinder.org
  ingressClassName: nginx

to

httpRoute:
  enabled: true
  hostnames:
    - staging.mybinder.org
  parentRefs:
    - kind: Gateway
      name: gateway-name

tls is handled on the Gateway instead of the Route, so there is no substitute for the tls config within this chart, that becomes entirely out of scope for the chart.

[consideRatio]

I appreciate this naming over z2jh's current naming that references a gateway instead of parentRefs, considering if we should align z2jh with this

[manics]

I had that thought too! The current Z2JH values have already been released though, so it would either be a breaking change, or require more complicated logic to provide backwards compatibility.

[minrk]

Yeah, I should have commented my reasoning here. This is based on having done a deployment with jupyterhub and prometheus/grafana, and I like the prometheus/grafana approach better, since it is a more straightforward passthrough of the specs.

Theirs do expose much more of the route to allow for other Gateway API versions, route types, rules, but I thought that was overkill for us for now, so this is a bit in between theirs and the one in z2jh.