chore(kbfile): sort catalog files by descending creation time (#209)

Because

- It is confusing to upload a file and then scrolling to the bottom to
  find it in the catalog file list

This commit

- Updates the list files repository method to sort by `create_time
DESC`.

Author: jvallesm

pkg/repository/knowledgebasefile.go

@@ -349,8 +349,10 @@ func (r *Repository) ListKnowledgeBaseFiles(ctx context.Context, uid string, own
 		query = query.Where(whereClause, kbfs[0].CreateTime)
 	}
 
-	// Order by create time
-	query = query.Order(fmt.Sprintf("%v ASC", KnowledgeBaseFileColumn.CreateTime))
+	// Order by create time DESC
+	// TODO INS-8162: the repository method (and the upstream handler) should
+	// take an `ordering` parameter so clients can choose the sorting.
+	query = query.Order(fmt.Sprintf("%v DESC", KnowledgeBaseFileColumn.CreateTime))
 
 	// Fetch the records
 	if err := query.Find(&kbs).Error; err != nil {