Make ECMQmlModule forward to upstream CMake macros for QML module creation

This splits ECMQmlModule into a version for Qt 5 that keeps the old behaviour and a version for Qt 6 that mostly acts as a forwarder to Qt's QML CMake macros like qt_add_qml_module. Arguments are mostly the same though some are deprecated when used with Qt 6 and any unparsed arguments will be forwarded to the Qt CMake macros. This should allow most of our existing QML modules to use it without requiring major porting effort.