🚀(helm) add a Redis cache service

This commit is working in progress. I have added an extra chart to take
benefits of the Redis operator developed by Indie hoster.

When using the dev environment, I used bitnami redis chart to deploy
a Redis service with authentication disable.

src/helm/extra/templates/keydb.yaml

@@ -0,0 +1,7 @@
+apiVersion: core.libre.sh/v1alpha1
+kind: Redis
+metadata:
+  name: redis
+  namespace: {{ .Release.Namespace | quote }}
+spec:
+  disableAuth: false