powerDownCommands is supposed to run before shutdown, but the current
implementation only runs before-sleep, thus not enabling wakeonlan on
devices when powering off even if the hardware supports it.
Taking into consideration the possibility of unexpected shutdown, it is
preferable to move the commands to powerUpCommands instead which is
executed at boot time as well as after resume - that should cover all
use cases for wakeonlan.
Fixes#91352
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
