Elnu's NixOS configuration

Make rofi power menu work by removing password requirement from shutdown, reboot, etc., which is normally done with visudo (see this Stack Overflow thread and Nix sudo option.
Package safe poweroff bash script required by rofi power menu
Theme lightdm
Theme GRUB
Find out how handling multiple hosts works so both desktop and ThinkPad configurations are buildable from flake
Load in vim configuration
Add yubikey login
Install and setup service for yubioath-desktop