nixos/rogue: Set WorkingDirectory to /tmp

Otherwise we can get an ugly /rogue.scr in the root of the filesystem
hierarchy.

Changed files
+1
nixos
modules
services
misc
+1
nixos/modules/services/misc/rogue.nix
···
TTYPath = "/dev/${cfg.tty}";
TTYReset = true;
TTYVTDisallocate = true;
+
WorkingDirectory = "/tmp";
Restart = "always";
};
};