This commit allows the MinIO server to parse the metadata if:
- either the `X-Minio-Internal-Server-Side-Encryption-S3-Key-Id`
and the `X-Minio-Internal-Server-Side-Encryption-S3-Kms-Sealed-Key`
entries are present.
- or *both* headers are not present.
This is in service to support a K/V data key store.