Create a container to embed Quick items into a native Android/iOS application

A very interesting feature would be to embed a QtQuick item into a native application. The idea would be to create the main UI items (navigation bar, drawer, toolbar, ...) using native views (e.g. with Java/Swift code or using wrappers like qtqmlandroid) and create the content using Quick 2 items.

This would be the contrary of https://bugreports.qt.io/browse/QTBUG-35648. While embedding a native view in the Qt quick scene graph seems to be a difficult challenge, embedding a Quick view in a native application seems technically more feasible as we could create a surface (like it is currently the case for Window items) and insert it into the native layout.

This would open new perspectives for developing cross-platform mobile applications by sharing components (e.g. Quick Controls 2) without completely giving up native UI.