Rust containers k8s

[StuartHarris]

Updates the rust containers scenario

• move from firestore to redis
• move from kafka to NATS
• add health endpoint to notification service
• validate inventory service sql against local db (using sqlx prepare and offline mode)
• update dependencies
• rework k8s manifests (and move from helm to kustomize)
• deploy and test against local k3d cluster (with k3d managed registry)
• update relevant github workflow