Support system.activationScripts

[BlueDrink9]

Is your feature request related to a problem? Please describe.

As a workaround for many of the missing nixos features, it would be useful to manually recreate some of the effects of nixos functions like system.udev, e.g. by reloading udev rules after creating etc."udev.d".file.rules

Describe the solution you'd like

Support system.activationScripts, even as just an alias for a set of shellcode to run at the end of the system manager processing.

Describe alternatives you've considered

Of course ideally system manager would support all of the nixos features, but that will take a lot longer, and this offers a workaround in the meanwhile.

Additional context

Currently we get

       error: The option `system' does not exist. Definition values:
       - In `/nix/store/if37c3y72809r7arpkqqafv0jhka34l5-source/nix/system-manager/modules':
           {
             activationScripts = {
               udev = {
                 text = ''
                   #!/nix/store/11ciq72n4fdv8rw6wgjgasfv4mjs1jrw-bash-5.2p37/bin/bash

[jrhadams]

As a new user, I would also be really in favor of this feature!

[dsully]

+1