Extend support for streaming datasets that use pathlib.Path.glob
I am thinking that ideally we should call `fs.glob()` instead... Thanks, @lhoestq: the idea of adding the mock filesystem is to avoid network calls and reduce testing time ;) 

I have added `rglob` as well and fixed some bugs.
This PR extends the support in streaming mode for datasets that use `pathlib`, by patching the method `pathlib.Path.glob`.

Related to #2874, #2866.

CC: @severo