Can't force qtwayland applications using wayland text input

The qtwayland will check QT_IM_MODULE env variant, if the env var is not empty, the qtwayland will using the input context of from QT_IM_MODULE. However, under normal circumstances, the wayland desktop environment will use XWayland to support X11 program running, so the Wayland desktop environment usually sets the QT_IM_MODULE environment variable the same as the X11 desktop environment. This will cause the Qt application to never use the wayland input context.