[cvas22]

What this PR does:

With ingress-nginx being retired, I added an optional Gateway API HTTPRoute for the cortex nginx service as an alternative to the existing ingress values.

When httpRoute.enabled is true (and nginx.enabled), the chart renders a gateway.networking.k8s.io/v1 HTTPRoute that sends traffic to the nginx service on the same port the Ingress uses. The new values:

• httpRoute.parentRefs: the Gateway(s) to attach to
• httpRoute.hostnames: hostnames (templated, like other values in the chart)
• httpRoute.matches: defaults to PathPrefix /, same as the Ingress default
• httpRoute.filters, httpRoute.annotations, httpRoute.labels

It is disabled by default, so existing installs render the same manifests.

Example:

httpRoute:
  enabled: true
  parentRefs:
    - name: my-gateway
      namespace: gateway-system
  hostnames:
    - cortex.example.com

Which issue(s) this PR fixes:
Fixes #602

Checklist

• CHANGELOG.md updated

Notes

I kept the route to a single rule that points at nginx, because nginx already does the per-path routing to the Cortex components. I didn't enable it in the ci/ values, since the test cluster may not have the Gateway API CRDs installed.