MCU: Fonts are not copied from QtDS to qmlproject and fonts folder

Fonts are not copied from QtDS to qmlproject and fonts folder. 

​This was already an issue with CMakeLists.txt. Should not be a big deal with qmlproject.

This affects both system fonts in QDS' font selector and the fonts from Bridges.

The font selector for MCU project should only offer the fonts declared in the project and the default font shipped with Qt for MCUs.
For fonts declared in Bridge imports, QDS should show a warning about missing font if they are not already declared in the project. For better user experience, we could provide an easy "wizard" to fix the missing fonts.

Custom fonts added to the project in the QDS UI (for example by dragging a font file into the FONTS category in the Assets tab) must be available to MCU projects.