helm chart uses outdated API version for ingress and should support ingressClassName

[brianmay]

W0909 09:08:48.099861  299554 warnings.go:70] extensions/v1beta1 Ingress is deprecated in v1.14+, unavailable in v1.22+; use networking.k8s.io/v1 Ingress
W0909 09:08:48.128581  299554 warnings.go:70] extensions/v1beta1 Ingress is deprecated in v1.14+, unavailable in v1.22+; use networking.k8s.io/v1 Ingress
W0909 09:08:48.245069  299554 warnings.go:70] extensions/v1beta1 Ingress is deprecated in v1.14+, unavailable in v1.22+; use networking.k8s.io/v1 Ingress

This is from:

# Source: keel/charts/keel/templates/ingress.yaml
apiVersion: extensions/v1beta1

Also it looks like the ingress chart doesn't support the ingressClassName which is required for ingress-nginx 4.0

https://kubernetes.io/blog/2020/04/02/improvements-to-the-ingress-api-in-kubernetes-1.18/#deprecating-the-ingress-class-annotation

Here is the change that is required to do that:

https://github.com/longhorn/longhorn/pull/2258/files