fix qrc generation for system with symlinks and always build the library

on e.g. macOS symlinks survived the cmake dir copy and the rcc compiler just did not add the symlinked files

now we handle both symlinks and windows pseudo link files the same way

always generate the icon library, we will require it in icon themes to ensure we are no longer missing icons on foreign desktop envs

ensures that the CI tests the code path we did only take in the patched craft builds