Add Gateway API support across Onyxia

Add support for Kubernetes Gateway API in Onyxia, starting with `HTTPRoute`, so Onyxia can work in clusters that expose applications through Gateway API

I was able to do it as an external manner already, adding httproute to the wrappers charts and forking the charts collection with httproute added.

I saw it was talked about [in the community call of january](https://docs.onyxia.sh/contributors-doc/community-calls/january-2026-community-call), but I don't know if implementation were already in motion .