Add tests for ONE_DIR commands
Add tests for ONE_DIR commands

Check that we consistenly reject specifying multiple
installations for commands that only accept one.

Closes: #2534
Approved by: alexlarsson

matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak