Test ingress chart against kong chart PRs

[rainest]

The ingress chart uses released versions of the kong chart. We want to test kong changes in the separate ingress Deployments as they're being proposed, rather than needing to release kong, open an ingress PR, and make further releases of kong if something broke.

Someone from the Kubernetes #charts chat noted that you can sorta do this:

I’ve just been using repository: file://../<chart_name> in the deps while testing (which works since all my charts live in the same repo). But that’s annoying because it requires editing my deps while I’m testing.

It'd need a hack to edit the ingress Chart.yaml, but absent other viable options it's worth a shot.