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.
We need to define our own copy constructor only
if an object has pointers or any runtime allocation
of the resource like file handle, a network connection..etc.
note: Default constructor does only shallow copy.
