Add feature: Launch Spectacle without taking screenshot

Feature request for https://bugs.kde.org/show_bug.cgi?id=437368

Works fine with spectacle -l.

Tho the title of Spectacle is the one of the last file -> https://invent.kde.org/aprcela/spectacle/-/blob/master/src/Gui/KSMainWindow.cpp#L378

ATM Does neither work with:

a) dbus call qdbus org.kde.Spectacle / OpenNoScreenshot - spectacle gets stuck for a while and then closes.

b) Launching with CTRL+Shift+PrntScrn , even tho I replaced the org.kde.spectacle.desktop file in /usr/share/applications and rebooted.