Enable IPv4/IPv6 Dual-Stack Services

[mike-matera]

Proposed change

The z2jh Helm chart should enable users to configure the ipFamilies and ipFamilyPolicy keys of the proxy-public service. I can confirm that manually editing the service resource to enable dual stack works for my application.

You can read about how dual stack services work on the Dual Stack in Kubernetes page.

This is probably only needed on the proxy-public service because that's the external facing service. However, it would be great to be able to make the whole system dual stack if users want to.

Alternative options

None

Who would use this feature?

IPv6 is quite easy to use in recent Kubernetes. Google, Amazon and Microsoft all support dual stack clusters. So almost everyone could use it.

(Optional): Suggest a solution

It's a relatively simple update to the service template. Time permitting, I'll send an example PR.