privacy: Enable USB protection in "lockscreen" mode by default
With this change, g-s-d will spawn the USB component which controls USBGuard. If the USBGuard is not present or its version is not compatible, it shuts down and should not affect the user's session.
USBGuard >= 0.7.5 is a soft-dependency. If it is installed and running (i.e. reachable via DBus), we control it. Otherwise the component rests in peace.
Edited by Tobias Mueller