feat: support kubernetes gateway api

[merll]

📌 Summary

This PR migrates from Ingress-Nginx to the Kubernetes Gateway API using Istio as an ingress gateway.

🔍 Reviewer Notes

There are two related PRs, that need to be considered during tests:

• feat: update manifests for gateway api apl-api#943: Required for Shell / TTY feature
• feat: separate services for selection by httproute apl-charts#42: Required for canary deployments

The migration process is implemented but requires changes in the following PR to work correctly. This should be merged first:

• fix: run pre- and post-upgrade consistently #3043

Since a custom values upgrade was extended after merging, when testing an upgrade from main, the following procedure must be followed:

1. disable auto-sync of apl-operator and scale down to 0, so that it does not sync while you make the following changes:

kubectl patch applications.argoproj.io -n argocd apl-operator-apl-operator --patch '[{"op": "remove", "path": "/spec/syncPolicy/automated"}]' --type=json
kubectl scale --replicas=0 -n apl-operator deployment apl-operator

2. lower spec.version in env/settings/versions.yaml to 55
3. optional: remove platformClass.annotations in env/settings/ingress.yaml
4. update ConfigMap otomi/otomi-status field deployingVersion to 4.16.0:

kubectl patch configmap otomi-status -n otomi --type merge -p '{"data":{"deployingVersion": "4.16.0"}}'

5. then the version can be set to this feature branch (APL-1595-2)
6. scale apl-operator back up

kubectl scale --replicas=1 -n apl-operator deployment apl-operator

The following related PR has already been merged to reduce the diff of this one. It includes the CRD and a base chart for generic setup of Gateways:

• feat: add Gateway API CRDs and essential chart #3030

🧹 Checklist

• Code is readable, maintainable, and robust.
• Unit tests added/updated