QDS: update MCU project template with new structure

The template MCU project in Qt Design Studio needs to be updated to include a .qmlproject with all the new properties and types defined in Qt for MCUs. 

The template .qmlproject should explicitly define all available properties, to make it easier for users to change these properties without having to look into the documentation for what is available.
Imported modules need to make use of the modules API added for MCU in .qmlproject

The generated template CMakeLists also need to be updated to include the new .qmlproject file, rather than adding QML and asset files using the old CMake API from Qt for MCUs 1.x.

If the qmlprojectexporter feature is first released as a Tech Preview, Qt DS should only offer to use it as an option, with an explicit warning about being not a stable feature.