build(cmake): mark nuget package includes as SYSTEM to suppress third-party warnings

[Shan-Zhou]

suppress warnings like

D:\a\DebugViewPP\DebugViewPP\application\nuget\packages\boost.1.80.0\lib\native\include\boost\asio\detail\impl\win_iocp_socket_service_base.ipp(629,26): warning C4242: '=': conversion from 'int' to 'ADDRESS_FAMILY', possible loss of data [D:\a\DebugViewPP\DebugViewPP\build\application\DebugViewppLib\DebugView++Lib.vcxproj]
  (compiling source file '../../../application/DebugViewppLib/DbgviewReader.cpp')
  
D:\a\DebugViewPP\DebugViewPP\application\nuget\packages\boost.1.80.0\lib\native\include\boost\asio\impl\serial_port_base.ipp(511,22): warning C4242: '=': conversion from 'const unsigned int' to 'BYTE', possible loss of data [D:\a\DebugViewPP\DebugViewPP\build\application\DebugViewppLib\DebugView++Lib.vcxproj]
  (compiling source file '../../../application/DebugViewppLib/DbgviewReader.cpp')