The aim of this commit is to easily build qelectrotech under windows
with qt6/cmake and the package tool MSYS2.
-Update some cmake file.
-Remove Git submodule for pugixml and single application
-Use cmake find_package for pugi xml
-Use cmake fetchContent for single application.
-Use cmake find_package for KCoreAddons and KWidgetsAddons.
-Minor change for pugi xml
-Minor change on ProjectPrintWindow class to compatible with Qt6 API.
Upgrade pugixml to be compatible with cmake >= 4.0.0.
Compatibility with CMake < 3.5 has been removed from CMake since 4.0.0.
Pugixml V1.11.4 used cmake 3.4. Latest version V1.15 use cmake VERSION
3.5...3.30
