Expose chrome://net-internals or API to clear HSTS entries

Sometimes it's necessary to clear a HSTS entry for a certain page, e.g. when testing whether HSTS works correctly, after accidentally misconfiguring a server during development, or when accidentally ending up with a HSTS entry for localhost.

In Chromium, this would typically be done by using chrome://net-internals since it doesn't seem to be available in e.g. the devtools.

Thus, this currently isn't possible with QtWebEngine - it'd be great to either have access to the net-internals page, or have something like a QWebEnginePage::clearHstsData(QUrl) (or perhaps QString, seeing that it's only a hostname).