Add a home-manager module to simplify installation and config management on nix systems. This greatly reduces the setup time and makes it integrate better with other programs on nix, mainly Hyprland which this module is based on.
Even though it isn't faster than Hyprland IPC, it still is more flexible and more future proof. Closes https://github.com/scorpion-26/gBar/issues/8
add nix support via a flake. Flake tested and builds successfully.