Ship GeckoLinux with DNF per default

[TobiPeterG]

Hey there,

I recently learned that OpenSUSE also supports installing DNF as package manager. It doesn't replace Zypper, but is rather able to work next to zypper.
As packagekit was remove due to issues, an alternative might be to ship DNF and it's packagekit backend, as they also do not block yast software all the time.
In general, DNF's packagekit implementation is way more mature than what zypper offers. This change would make GeckoLinux even more beginner friendly.
Also, it wouldn't remove any functionality as zypper isn't removed. DNF also has plugins for snapper to work etc.

WIth this change, it would also be good to ship with appstream to show applications from the repos in a packagekit frontend like gnome software or discover.
This also allows automatic offline updates to work properly, as dependencies can be resolved automatically