Return the committed object or part time on federation write responses and
capture it for CopyObject and UploadPartCopy without a follow-up read.
Keep successful writes compatible with targets that do not supply a time.
Reject authenticated raw SSE-C replica CopyObject across deployments before
forwarding. Extend the existing SSE fixtures to verify empty objects,
stored checksums, KMS contexts and multipart sources.
Refs: #169, #168, #171
Signed-off-by: Feng Ruohang <rh@vonng.com>
Feng Ruohang