feat(storage): allow specifying includeTrailingDelimiter

References fsouza/fake-gcs-server#676.

storage/bucket.go

@@ -1543,6 +1543,7 @@ func (it *ObjectIterator) fetch(pageSize int, pageToken string) (string, error)
 	req.StartOffset(it.query.StartOffset)
 	req.EndOffset(it.query.EndOffset)
 	req.Versions(it.query.Versions)
+	req.IncludeTrailingDelimiter(it.query.IncludeTrailingDelimiter)
 	if len(it.query.fieldSelection) > 0 {
 		req.Fields("nextPageToken", googleapi.Field(it.query.fieldSelection))
 	}

storage/storage.go

@@ -1588,6 +1588,11 @@ type Query struct {
 	// which returns all properties. Passing ProjectionNoACL will omit Owner and ACL,
 	// which may improve performance when listing many objects.
 	Projection Projection
+
+	// If true, objects that end in exactly one instance of delimiter have
+	// their metadata included in items[] in addition to the relevant part of
+	// the object name appearing in prefixes[].
+	IncludeTrailingDelimiter bool
 }
 
 // attrToFieldMap maps the field names of ObjectAttrs to the underlying field