feat: add eurkey to base.lst
eurkey is a great layout for lots of people. to make it easy to use, we would like to see it in calamares (https://github.com/calamares/calamares/issues/2078).
The proposal was to add it to the /usr/share/X11/xkb/rules/base.lst, which is being read by calamares.
I do not fully understand what the distinction betweek the base.extras.xml and the base.xml is.