packagekit-qt: Move to libsForQt5 scope.
packagekit-qt: Move to libsForQt5 scope.

Since it's a dependency of kde's "discover", it's best to define it
there to avoid a possible mixed qt5 versions usage (#101369).

NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs