add CopyObject optimization when source and destination are same (#10170)

when source and destination are same and versioning is enabled
on the destination bucket - we do not need to re-create the entire
object once again to optimize on space utilization.

Cases this PR is not supporting

- any pre-existing legacy object will not
  be preserved in this manner, meaning a new
  dataDir will be created.

- key-rotation and storage class changes
  of course will never re-use the dataDir

cmd/erasure-metadata.go

@@ -112,6 +112,7 @@ func (fi FileInfo) ToObjectInfo(bucket, object string) ObjectInfo {
 		DeleteMarker:    fi.Deleted,
 		Size:            fi.Size,
 		ModTime:         fi.ModTime,
+		Legacy:          fi.XLV1,
 		ContentType:     fi.Metadata["content-type"],
 		ContentEncoding: fi.Metadata["content-encoding"],
 	}