Helm chart option for handling HTTP/2 behind an Ingress controller

**Describe the desired outcome from the user's perspective**
As a DevOps admin, I want to easily configure HTTP/2 from the client to my ingress controller and from the ingress controller to Zilla.

**Acceptance criteria**
 - add an option to enable [HTTP/2 through an ingress controller](https://stackoverflow.com/questions/67471377/using-http-2-with-nginx-ingress-on-gke) by default
