Ahmad Samir authored Jun 09, 2022 and Tomaz Canabrava committed Jun 11, 2022

This way we don't run the same migration stuff at every start.

This also fixes an issue with the widget colorscheme config entry; if the
old WindowColorScheme key isn't found an empty string is used to write the
new UiSettings/ColorScheme key.

Inspired by similar code in KIO (SystemBookMarks related code) and Dolphin.