Initialize the offscreen platform plugin with no screens,
create QGuiApplication object.
Not much of the high-dpi related Qt API can be used
in this configuration, but at least Qt should not crash
on startup.
Task-number: QTBUG-71034
Change-Id: I6620843c3bd8b692c5c2419b1ba290e16175ba5b
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>