feat: make wlr portal working for screenshare

feat: use custom session start script instead of DM

chore: move renamed options

refactor: modularize the configuration

chore: remove unnecessary code, use modules instead of imports, split files

chore: update deprecated options

fix: correctly split options in xkbOptions

feat: add natural scrolling, and map caps lock to ctrl

feat: toggle layout with alt shift

chore: split default xserver configuration to desktop/default