config2.py: Handle PermissionError while creating user-config directory
config2.py: Handle PermissionError while creating user-config directory

There is no need to check for `os.path.isdir(dir)` condition. `os.makedirs`
will do that automatically and will raise `OSError` if `dir` exists.

Note that PermissionError is a subclass of OSError that does not exist in PY2.

Bug: T185082
Change-Id: Ifac3120b9deccb3d543fb9fc1f28ac6677dac252

wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core,wikimedia/pywikibot-core