Add appProtocol field to all ServicePorts (#7493)

Minor update to the helm chart to set the [appProtocol][1] field on all
http / https ports defined in the various services created by the helm
chart:

- http and https for controller-service
- http and https for controller-service-internal
- https for controler-service-webhook
- http for default-backend-service

These are only added in kubernetes >= 1.20, which is when this feature
became stable.

[1]: https://kubernetes.io/docs/concepts/services-networking/service/#application-protocol

charts/ingress-nginx/templates/default-backend-service.yaml

@@ -29,6 +29,9 @@ spec:
       port: {{ .Values.defaultBackend.service.servicePort }}
       protocol: TCP
       targetPort: http
+    {{- if semverCompare ">=1.20" .Capabilities.KubeVersion.Version }}
+      appProtocol: http
+    {{- end }}
   selector:
     {{- include "ingress-nginx.selectorLabels" . | nindent 4 }}
     app.kubernetes.io/component: default-backend