Return value format of `epath.Path.stat()` does not match `pathlib.Path.stat()`

[ayaka14732]

Format of epath.Path.stat():

https://github.com/google/etils/blob/v1.9.2/etils/epath/stat_utils.py#L21-L39

Format of pathlib.Path.stat():

https://docs.python.org/3/library/os.html#os.stat_result

Apart from the attribute name differences, the attribute that I am currently interested in is pathlib.Path.stat().st_mtime_ns, which represents mtime in nanoseconds. However, epath.Path.stat() does not return this information.