Offer a CMake equivalent for qmake -project

-project       Put qmake into project file generation mode
                 In this mode qmake interprets [files] as files to
                 be added to the .pro file. By default, all files with
                 known source extensions are added.
                 Note: The created .pro file probably will
                 need to be edited. For example add the QT variable to
                 specify what modules are required.