NO GUI QEMU test running

[D3vil0p3r]

What would you like to be added:
Adding an argument that allows you to run tests without opening the QEMU GUI windows.

Why is this needed:
It is useful for those that need to operate on a tty environment or don't have a GUI interface, like CI/CD workflows.

Currently by CI/CD workflow environment (for example in a docker container), since there is not a GUI, the test works correctly, but at the end of quicktest, notify-send command produces:

Cannot autolaunch D-Bus without X11 $DISPLAY

Could you prevent this error and make quicktest to work also in a non-GUI environment?