Enable windows tests again, the first steps (#528)

[halfow]

To allow for the CI to run the windows tests again, I've done the bare minimum to get the tox test runner to run again under Windows. There are failing tests but, the purpose of this pull request is just to make it run again.

• Resolve XDG paths in a OS independent way (using pathlib.Path to do all \ and / convertions)
• Create directories for config file if they doesn't exist.
• Workaround for removal of tmp XDG files on windows. shutil.rmtree sometimes fails one windows, seems to be UAC related.

Needs to run on the CI for Linux verdict just tested for python versions 3{6-11} on windows 11 😄

[olofk]

Excellent! Thank you for working on this. Picked and pushed!