Use user-based configuration settings in script_wui.py
Use user-based configuration settings in script_wui.py

And also a nice error message when it doesn't exist.

Bug: T70797
Change-Id: I7486e66df0c05b490f1e8cc95c28b74e370fe90a

hasteur/g13bot_tools_new,happy5214/pywikibot-core,wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core,jayvdb/pywikibot-core,hasteur/g13bot_tools_new,hasteur/g13bot_tools_new,magul/pywikibot-core,wikimedia/pywikibot-core,happy5214/pywikibot-core,magul/pywikibot-core,Darkdadaah/pywikibot-core,npdoty/pywikibot,Darkdadaah/pywikibot-core,jayvdb/pywikibot-core,npdoty/pywikibot