FSFile should support any PathLike objects

[gerritholl]

Feature Request

Is your feature request related to a problem? Please describe.

When the FSFile constructor is passed anything that isn't a string, the FSFile.__str__ method triggers a TypeError:

import pathlib
from satpy.readers import FSFile
from fsspec.implementations.local import LocalFileSystem
fsf = FSFile(pathlib.Path("/tmp/abc"), LocalFileSystem())
print(str(fsf))

which gives:

Traceback (most recent call last):
  File "mwe/mwe002.py", line 5, in <module>
    print(str(fsf))
TypeError: __str__ returned non-string (type PosixPath)

This is not a bug because the FSFile docstring does state it expects a string, but it would be nice if other pathlike objects could be passed as well.

Describe the solution you'd like

I would like that the FSFile constructor supports the file system protocol, such that the code above would work as intended.

Describe any changes to existing user workflow

None reasonably expected.

Additional context

It would save me a call to __fspath__ or str(...) prior to creating the FSFile objects.