use pathlib?

[mathause]

Need to try it out e.g. the glob part or if path.format works.

[mathause]

We could also return pathlib objects

[mathause]

maybe add a as_posixpath (or to_posixpath) or to_pathlib to FileContainer which creates a list of pathlib.PosixPath

[mathause]

We could also return pathlib objects

Could be good for create_filename but still unsure about the API.

So xarray uses

def open_dataset(path: str | os.PathLike[Any], ...):

    if isinstance(path, os.PathLike):
        path = os.fspath(path)

Which we can also do - for the input to FileFinder.