NATS: Auto-provision NATS resources

[mfreeman451]

When we create a new user and assign them an 'instanceId', we need to create a new account in NATS JetStream, with a user that contains the NKEY to auth.

https://docs.nats.io/running-a-nats-service/configuration/securing_nats/accounts

Another possible auth strategy, Auth Callout - https://docs.nats.io/running-a-nats-service/configuration/securing_nats/auth_callout

Need to look into running NATS in operator mode.

• [x] #115
• [x] #116
• [ ] Create account named after instanceId
• [x] Create and Securely store NKEYs
• [ ] #113