Add k8s v1.22 support for nginx IngressClass

[stephen-soltesz]

Our nginx configuration in prometheus-federation cluster is preventing the GKE upgrade from v1.21 to v1.22.

According to https://kubernetes.github.io/ingress-nginx/ v1.22 requires an IngressClass definition. This new object is created automatically by helm using a recent version of the ingress-nginx chart.

Before the upgrade, nginx would start with log messages reporting it was using the networking.k8s.io/v1beta1 API. Now, log messages include the correct v1 API.

I0811 15:44:06.469617       7 event.go:285] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"reboot-api-tls", UID:"64bf34ac-6dbd-11e9-9342-42010a8001cf", APIVersion:"networking.k8s.io/v1", ResourceVersion:"785029223", FieldPath:""}): type: 'Normal' reason: 'Sync' Scheduled for sync
I0811 15:44:06.470038       7 event.go:285] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"prometheus-tls-basic", UID:"ac35da90-fdd6-46c7-aad0-33b56832509a", APIVersion:"networking.k8s.io/v1", ResourceVersion:"785029224", FieldPath:""}): type: 'Normal' reason: 'Sync' Scheduled for sync
I0811 15:44:06.663410       7 event.go:285] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"grafana-tls", UID:"79546f2c-2e0e-11e8-a80f-42010a8000e8", APIVersion:"networking.k8s.io/v1", ResourceVersion:"785029227", FieldPath:""}): type: 'Normal' reason: 'Sync' Scheduled for sync
I0811 15:44:06.861695       7 event.go:285] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"alertmanager-tls", UID:"791aa492-2e0e-11e8-a80f-42010a8000e8", APIVersion:"networking.k8s.io/v1", ResourceVersion:"785029231", FieldPath:""}): type: 'Normal' reason: 'Sync' Scheduled for sync
I0811 15:44:07.061625       7 event.go:285] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"grafana-tls-oauth", UID:"42828cc8-b2d3-44fa-9668-49c15b66cd43", APIVersion:"networking.k8s.io/v1", ResourceVersion:"785029233", FieldPath:""}): type: 'Normal' reason: 'Sync' Scheduled for sync
I0811 15:44:07.262254       7 event.go:285] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"prometheus-tls", UID:"f9be5695-8657-467f-a0b6-04e33a4ca437", APIVersion:"networking.k8s.io/v1", ResourceVersion:"785029234", FieldPath:""}): type: 'Normal' reason: 'Sync' Scheduled for sync
I0811 15:44:07.462859       7 event.go:285] Event(v1.ObjectReference{Kind:"Ingress", Namespace:"default", Name:"prometheus-tls-oauth", UID:"67540dba-2f38-45cd-97bd-b1c5e960ff45", APIVersion:"networking.k8s.io/v1", ResourceVersion:"785029237", FieldPa

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This change is 

[nkinkade]

Reviewed 4 of 4 files at r1, all commit messages.
Reviewable status: complete! 1 of 1 approvals obtained

[stephen-soltesz]

Thank you!

[stephen-soltesz]

Part of #937