add safe-mode to start gnome-shell without extensions
@pointhi
Submitted by Thomas Pointhuber Link to original bug (#795761)
Description
Current Behaviour
gnome-shell crashes, login back again and hope it does not immediately crash again
Expected Behaviour
if gnome-shell crashes, add some option to start it in "safe-mode", where for example extensions are disabled (a common cause of crashes)
Version: 3.28.x