Add gateway API routes to flagd CRD

[lukas-reining]

#615 with the implementation in #633 brought in a new CRD for deploying a standalone flagd with service and optional ingress.
I would like to have the option to deploy matching Gateway API routes instead of an ingress with the increasing adoption of Gateway API.

I will open a PR the next days if no arguments against that come up before :)

cc @open-feature/cloud-native-maintainers @toddbaert @beeme1mr