s3: list directory key objects in versioned bucket version listings (#9842)

ListObjectVersions gated explicit directory objects on Mime ==
FolderMimeType, but an SDK PutObject of "dir/" carries a default
Content-Type (e.g. application/octet-stream), so those directory keys
were dropped from the version listing while ListObjectsV2 - which keys
off IsDirectoryKeyObject (any non-empty mime) - still showed them. Use
the same IsDirectoryKeyObject check so the two listings agree.

The directory test's storage-class assertion compared an ObjectStorageClass
constant against ObjectVersion.StorageClass (ObjectVersionStorageClass);
the values matched but the SDK enum types did not, so it only surfaced
once the directories started appearing. Use the matching constant.

weed/s3api/s3api_object_versioning.go

@@ -802,8 +802,11 @@ func (vc *versionCollector) collectVersions(currentPath, relativePath string) er
 
 // processDirectory handles directory entries
 func (vc *versionCollector) processDirectory(currentPath, entryPath string, entry *filer_pb.Entry) error {
-	// Handle explicit S3 directory object
-	if entry.Attributes.Mime == s3_constants.FolderMimeType {
+	// Handle explicit S3 directory object. Match ListObjectsV2's
+	// IsDirectoryKeyObject (any non-empty mime), not just FolderMimeType:
+	// an SDK PutObject of "dir/" carries a default Content-Type, so the two
+	// listings must agree on what counts as a directory key.
+	if entry.IsDirectoryKeyObject() {
 		vc.processExplicitDirectory(entryPath, entry)
 	}