🚀(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/env.d/dev/values.desk.yaml.gotmpl

@@ -34,6 +34,7 @@ backend:
     POSTGRES_DB: people
     POSTGRES_USER: dinum
     POSTGRES_PASSWORD: pass
+    REDIS_URL: redis://default:pass@redis-master:6379/1
 
 frontend:
   image: