[5.0] Stream handling in NATS (important for configuring with Kubernetes/Helm Charts)

[mmattel]

References:
owncloud/ocis#7023 (Specify NATS stream replicas)
owncloud/ocis#7119 (NATS cache support memory storage / replicas)

Absolutely necessary for HA configs

Just a collection of keywords as reminder

• nats toolbox or nack
• nats deployment example
• externes nats --> streams settings
• caches must be available
• message bus needs a stream configuration
• more settings necessary as replicas present
• streams can and must be refied in configuration, per stream like TTL
• kubernes can only handle one config type per cache or stream
  (because ther is only one setting type per use case)
  (our HC example has for cache or stream anyways only one type)
  compared to single binary where one can defines caches and stores per service