Add secrets/certificate management bundle

[coryodaniel]

Create a secrets/certificate vault bundle (good vague term that works across AWS/GCP/Azure).

Cloud-agnostic abstraction for:

• AWS Secrets Manager / Parameter Store
• GCP Secret Manager
• Azure Key Vault

Should produce an artifact that applications can consume for:

• Storing and retrieving secrets
• Managing certificates/keys
• Accessing vault endpoints and permissions

Good example of cross-cloud abstraction.