Completions for dnf5

[mochaaP]

https://fedoraproject.org/wiki/Changes/ReplaceDnfWithDnf5

DNF5 just landed in Fedora rawhide and provides the dnf command by default.
Since DNF5 is built on libdnf5 and introduced many changes, it should now be a good time to start providing completions for the dnf5 command.

[faho]

According to https://dnf5.readthedocs.io/en/latest/changes.html#changes-on-the-command-line it's mostly a removal of unused features.

That means it shouldn't really impact us much, for now - we can't really remove the old syntax until nobody uses it anymore (i.e. until only Fedora versions with dnf5 are still supported).

[mochaaP]

We could provide a dnf5.fish though. This won't break the original dnf, while providing a more updated completion for dnf5 users.

[faho]

It won't be of much use - people will keep using dnf <TAB>.

[mochaaP]

Vendors could ship an config file with alias dnf=dnf5 if dnf5 was the default provider for /usr/bin/dnf

[faho]

They won't. They'll ship a symlink.

Vendors do not tend to configure fish.