Update nginx-ingress from v0.30.0 to v0.32.0

* Add support for IngressClass and RBAC authorization
* Since our nginx ingress controller example uses the flag
`--ingress-class=public`, add an IngressClass to go along
with it

Rel: https://kubernetes.io/docs/concepts/services-networking/ingress/#ingress-class

addons/nginx-ingress/aws/rbac/cluster-role.yaml

@@ -51,3 +51,12 @@ rules:
       - ingresses/status
     verbs:
       - update
+  - apiGroups:
+      - "networking.k8s.io"
+    resources:
+      - ingressclasses
+    verbs:
+      - get
+      - list
+      - watch
+