fix build issues

[xLPMG]

Fixes most build issues. Remaining issues are:

• Linux Qt6 Core build: the newly added files require further dependencies. I'm not sure how to solve this without bloating the core build
• Qt5 builds: QList and QPolygonF& are mixed. While Qt6 doesnt seem to have a problem with this, Qt5 does. This should be fixed but is not directly related to cmake

[github-actions]

Great PR! Please pay attention to the following items before merging:

Files matching src/**/*.cpp:

• Are possibly unused includes removed?

This is an automatically generated QA checklist based on modified files.