fix(helm): add ingressClassName support to Helm chart

Adds `ingress.className` value and renders `ingressClassName` in the
Ingress spec, allowing users to specify the ingress controller class.
Closes #377.

chart/values.yaml

@@ -97,6 +97,7 @@ resources:
 
 ingress:
   enabled: false
+  className: ""
   annotations: {}
   hosts:
     - host: chart-example.local