DRAFT: systemd/postmarketos-base-systemd: add trigger to run preset-all

This adds a trigger to postmarketos-base-systemd that runs systemctl preset-all any time unit files are changed on the system. This means we can drop the systemd macro for pkg pre-install/de-install scripts, and avoid making abuild complicated for handling systemd stuff.

The downside with this approach is that users who want to permanently disable can no longer do systemctl disable <unit>, and instead have to do systemctl mask <unit>. Given how much this improves other stuff, especially wrt upstreaming the abuild split func stuff, I think this is a worthwhile trade-off. We can always improve on this more in the future, since this trigger thing would be easy to rollback/replace.

fixes #3494 (closed)

Also see: #3476 Also see: #2804

@jane400 @caleb @whynothugo @pabloyoyoista : Your input would be appreciated

TODO:

• What about cleaning up links made from systemd preset that are broken after a pkg providing the enabled unit file was removed? This could be copied from the systemd macro's pre-deinstall func and included in the trigger somehow?

• Should this also run systemctl daemon-reload ?