Fixes bug [53826](https://bugs.winehq.org/show_bug.cgi?id=53826).
-- v20: ntdll/tests: Increase margins in timer merging tests. ntdll: Set xattr in NtCreateFile if inferred and requested attributes don't match. ntdll: Only infer hidden attribute from file name if xattr is not present. ntdll: Handle hidden file names inside get_file_info instead of after it. ntdll: Do not open-code hidden file handling in get_dir_data_entry. ntdll/tests: Add test for file attributes of files with names beginning with a dot.