Previously the parameters were just dropped. Now they can be read
from within the handler script. An example to show this is added.

Makes use of the new writeShellScript function as suggested in:
issue #21557

resolves: #21557

Motivation for this change

Previously the script for a certain event was run with no further information. This is fine for a button event where an action is executed on every press. But for something like ac_adapter we want to know what state the connection changed to.

To find out what the parameters are, you can listen to the socket with: nc -U /var/run/acpid.socket

Things done

• Pass parameter with '%e' argument
• Add example which takes advantage of parameters
• Add and use new writeShellScript function

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests). There are no tests
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/) no binaries because is a module
• Fits CONTRIBUTING.md.