feat(linux): Remove message box if same kbd version already installed

We no longer ask the user if he tries to install a keyboard that is
already installed with the same version. The only time we ask is for
downgrades.

A similar change is implemented in `km-package-install` where we
changed the logic to match `install_window.py`. We now silently
install the new version unless it's a downgrade in which case we
output a error message and exit. This change also introduces the
`--force` parameter which allows to install the downgrade. For
upgrades or re-installing the same version it will cause an
uninstall of the current version first.