First boot setup wizard and tuigreet integration
This MR is the first end-to-end try of implementing the new System Image V5 onboarding:
- Unless setup is completed, agetty autologins "root" (which has no pw anyway)
- The shell starts reform-setup in a special sway environment via a script in /etc/profile.d
- This sway is configured by the file /etc/reform-setup-sway-config
- 
greetdis installed (via Debian) andtuigreetbinary dropped in/usr/bin
- Reform Setup Wizard writes /etc/greetd/config.tomlwith sway or wayfire preselected (users can change this in tuigreet or in this file)
- After successfuly completion, Reform Setup Wizard runs its cleanup.shwhich 1. removes root autologin 2. removes itself from/etc/profile.d3. enables and starts greetd