Regression: QQuickControlsTestUtils does not compile for WebAssembly shared libraries build

A recent change to QQuickControlsTestUtils (fc683799) adds a qt_internal_add_qml_module() call to src/quickcontrolstestutils/CMakeLists.txt, in addition to the existing qt_internal_add_module() call.

This causes cmake to generate a build rule for libquickcontrolstestutilsprivateplugin.so which links against libquickcontrolstestutilsprivateplugin.a twice - it is listed twice on the LINK_LIBRARIES line in build.ninja.

This works fine on macOS (tested), but fails on Emscripten where we get "duplicate symbol" errors:

wasm-ld: error: duplicate symbol: QQuickControlsTestUtils::ComponentCreator::qt_static_metacall(QObject*, QMetaObject::Call, int, void**)
>>> defined in qtbase/lib/libQt6QuickControlsTestUtils.a(mocs_compilation.cpp.o)
>>> defined in qtbase/lib/libQt6QuickControlsTestUtils.a(mocs_compilation.cpp.o)