nixos/flashprog: Introduce flashprog module

Introduce the flashprog module. By enabling, its udev rules are applied
in addition to installing the package.

Signed-off-by: Felix Singer <felixsinger@posteo.net>

nixos/modules/module-list.nix

@@ -199,6 +199,7 @@
   ./programs/firefox.nix
   ./programs/firejail.nix
   ./programs/fish.nix
+  ./programs/flashprog.nix
   ./programs/flashrom.nix
   ./programs/flexoptix-app.nix
   ./programs/foot