QSslSocket / QNAM to ask for client certificate if the server selectively requires it

A server could require client certificate only in certain situations. For example a web server could be configured to require client certificate only for certain API end points. In Apache that seems possible like this:

https://httpd.apache.org/docs/2.4/mod/mod_ssl.html#sslverifyclient

But when connecting to such server with Qt there does not seem to be any indication that the server started renegotiation and now it also wants a client certificate.

This is not limited to HTTPS so it should be possible to handle with QSslSocket.

There also seems to be a related task: QTBUG-30182