AWS Transfer Family now supports AWS Secrets Manager storage for SFTP server host keys

Summary

• Adds support for storing SFTP server host keys in AWS Secrets Manager, enabling retrieval and reuse across servers and regions.
• Allows migration of existing host keys to Secrets Manager with IAM policies controlling access to private key material.
• Simplifies failover and server migrations by reusing the same host key without requiring clients to trust a new key.