Provide conan.io recipe (conanfile.py) which is in sync with Qt build configure script

Motivation:

A lot of companies are integrating external library dependency management into their build (CI) tool chains. It is necessary to keep track of used compiler versions, propagation of necessary compiler flags, as well as the build configuration of the external library itself. All this can be achieved by conan.io, which integrates nicely in the most used build management environments (like cmake, VS-Studio, etc.).

There exist some community effort to provide conan recipes for the Qt lib. But maintaining this is a complex task of encapsulate the Qt build configure interface into the conan options. This is an example project: https://github.com/cguentherTUChemnitz/conan-Qt.

Benefits:

When the conan.io recipe would be provided by Qt itself, the gap between the conan configuration and the Qt build configure script could be closed as much as possible. I think this would be beneficial for many companies to make their Qt libs dependency management more robust and it enables some kind of automatic external lib update testing in their CI pipelines.