Update knsrc to use kpackagetool5 commands

kwinswitcher.knsrc, kwinscripts.knsrc, kwineffect.knsrc

It seems the kwineffect.desktop was (and still is) invalid, as it
does not show up in `kpackagetool5 --list-types`.

To test, I overwrite the /etc/xdg/*.knsrc,
then opened the GHNS dialogs and installed stuff.

Differential Revision: https://phabricator.kde.org/D12249