Add option to enable persistence on Redis pod

[LucasMrqes]

As deployed by the helm chart, the redis pod does not have a mounted volume. Hence, when the redis server gets terminated (e.g. Kubernetes node renewed), the status of eveyr layer becomes "Error getting last result".

It would be nice to be able to activate persistence for Redis with a redis.peristence.enabled option in values file.

[Alan-pad]

Redis will be deprecated in the upcoming release, introducing a real long-term storage solution