Only expose "Plasma addons" from KNS when XDG_CURRENT_DESKTOP is KDE
At the moment, Plasma addons will be shown as a category item regardless of whether or not the desktop environment that Discover is running on is Plasma. I would like to ship Discover as the preferred graphical frontend package manager on Fedora Budgie Spin and more importantly Fedora Budgie Atomic, as Discover's rpm-ostree backend should enable rebasing to the correct Fedora ostree variant. See this Fedora Budgie SIG issue if you'd like to know what happens when a variant is hardcoded!
I would like to propose that Discover checks if the XDG_CURRENT_DESKTOP equals KDE
and only adds Plasma Addons if that is the case.
This may also provide a good opportunity for other desktop environments (or Fedora Spins) to leverage the fine work done on Discover. LxQT perhaps?
I have taken a cursory look at the KNSBackend at https://invent.kde.org/plasma/discover/-/blob/master/libdiscover/backends/KNSBackend/KNSBackend.cpp#L138 and I think it may be related to the logic on L253, however I'm not familiar enough with KNewStuff to make a judgement on where adding a check would be.
Happy to do the work on this if it seems like a sensible solution, just let me know where I should point myself!
Note: I would like to keep Application Addons as a category item, categories like File Templates (SDK) have some useful stuff!