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/templates/ingress.yaml

@@ -10,6 +10,9 @@ metadata:
     {{- toYaml . | nindent 4 }}
   {{- end }}
 spec:
+  {{- if .Values.ingress.className }}
+  ingressClassName: {{ .Values.ingress.className }}
+  {{- end }}
   {{- if .Values.ingress.tls }}
   tls:
     {{- toYaml .Values.ingress.tls | nindent 4 }}