[FYRA-63] Online updates on PackageKit

[korewaChino]

Right now, Fedora offers an update backend through PackageKit only in the form of DNF offline updates, which is good for some cases (i.e Kernel updates, kernel modules). But for non-core system upgrades there should be a way to apply updates live without having to reboot.

It's a minor UX problem as it doesn't really affect the system, but some users see it as too "icky" to have offline updates coming from Windows where the experience is basically everything is an offline update and users are forced to do the same workflow for updates on Fedora (but instead of it being optional they're forced to do it everytime an update comes out, ofc).

There should be an option to toggle that or something, since in Cockpit (specifically, the software updates module) there's system upgrades for applying updates live and an option to reboot later.

https://linear.app/fyra/issue/FYRA-63/online-updates-via-packagekit