Set `archinstall` as a note on installed packages

[Torxed]

Upstream patch that needs to be merged first: https://gitlab.archlinux.org/pacman/pacman/-/commit/2b1ca6c298629723ca334a596f8499dc331c9074

This would allow users in post-installation to dissect which packages were explicitly installed by archinstall for the user.

Small QoL and should be easy as an entry job for people willing to contribute :)