MCU: import from Qt Bridge into root of project

When doing import using Qt Bridge into QDS, QML and assets are imported into a subfolder by default (see screenshot below)

This is an issue with Qt for MCUs, since any QML located in subfolders need to be declared as QML module, requiring users to manually modify the project's CMakeLists.txt before being able to compile the project for MCU.

The ideal workflow is that a QDS project would always be compilable for MCU without any mandatory manual change. To achieve that, Qt Bridge import for MCU projects could always import QML files into the root directory of the project. Assets on the other hand can be in a "assets" subfolder, but also at the root of the project.

This will potentially cause name-conflict issues when multiple imports are done. A solution might be needed to deal with that.