In XMLHttpRequest, we need to get the QNetworkAccessManager from the
engine. However, if the request originates from a WorkerScript, there
exists no qmlEngine. We therefore add a new indirection to access the
QNAM, and set it up accordinly in registerWorkerScript.
Fixes: QTBUG-81055
Change-Id: I8915202b6d6b7139c8386304b3d1d7a22a82045e
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>
Fabian Kosmale