Fixed git self-updated & Created support for pseudo-booting the installed OS

Created by: Torxed

• Uses systemd-nspawn to pseudo-boot the installed OS for more elaborate installation steps
• Added triggers that can be used to react to certain things in the booted subsystem
• Almost all previous run() commands now use sys_command() in case future changes requires integration
• sys_command can also interact with protected tty integrations, such as ssh password requests.
• Added a lot more debug information and some smaller error handlers
• Fixed the git self-updated to actually work.. Haven't done in a while.