QWebEngine: support link clicked signal or other way of intercepting clicked links, as was avail in QWebKit

As documented here:
https://wiki.qt.io/QtWebEnginePortingFromQtWebKit
and discussed in Aug 2015 interest email list (Jean-Francois Dockes said he was going to create a feature request, but I couldn't find it – mark this as a dupe if you can!), there is no replacement for QWebPage::setLinkDelegationPolicy

The QWebChannel appears to be quite powerful, but requires custom javascript code.

Our application relies extensively on trapping the URL's that people click on, on a mediawiki wiki website, which then drives certain functionality in our app directly (in C++). The URL's are formatted with extra "command" information in their link and property structure. This is easily achieved with simple mediawiki templates and users can easily type in the necessary URL's to access whatever they want in our app. It is not clear how difficult the corresponding javascript / webchannel option would be.

Thus, it would be huge for us and I suspect many others who have relied on a similar strategy to have something like the original link click tracking capability from QWebPage. Thanks!