lumina: fix kwindowsystem and oxygen-icons5 attributes

[romildo]

Motivation for this change

The attributes qt5.kwindowsystem and qt5.oxygen-icons5 are not found after the Qt and KDE related packages have been reorganized. See #23180 and #23239.

/cc @ttuegel

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

[mention-bot]

@romildo, thanks for your PR! By analyzing the history of the files in this pull request, we identified @ttuegel to be a potential reviewer.