Selecting interface to use in QNetworkAccessManager

One feature people want back from symbian days is the ability to select which interface should be used for the network connectivity in QNetworkAccessManager (and for convenience/testability also should be added to QAbstractSocket). This feature has not been available through bearer management since its removal some 10 or so years ago.

In the end users should be able to select a network interface on which http/other protocol should be performed on. This is only includes choosing from the list that QNetworkInterface::allInterfaces() returns.

Motivations for this include avoiding known metered devices in controlled systems or simply selecting a non-default interface in certain cases.