Implement non-prefix builds if possible

QMake supports the concept of a no prefix build, where you do not have to run make install to use the Qt version. It is implicitly enabled when using -developer-build.

If possible we should try and implement that with the CMake Port. This greatly facilitates shortening the write code/build/test time for developers.

This means we need to export Config and Targets files which reference build tree artifacts and not an installed Qt location. These Config files will then be used by leaf modules by way of find_package()
These Config files would probably be the same that we need to support a super build.