read .ssh/config for parameters

[ccneko]

Hi! Just got a feature idea that might be a nice-to-have maybe?: supporting taking .ssh/config for parameters

i.e. just like we do sftp nickname in console, maybe we could connect as fsspec.filesystem('sftp', host='nickname') instead of fsspec.filesystem('sftp', host='XXX.XXX.XXX.XXX', port=XXX, username='XXX', password='XXX'), so we can have less hard coding and won't be saving passwords in plain text.

I raised a question on StackOverflow being unsure before, and now checking out after receiving a comment. https://stackoverflow.com/questions/65050701/can-python-package-fsspec-read-ssh-config?noredirect=1#comment115916870_65050701

Great thanks for the effort for the great package!