printf-stdarg.c seems have to been moved by mistake when moving logging sources to a common folder.
Also, because logging.c is specific to Windows, it is moved to FreeRTOS-Plus/Demo/Common/Logging/Logging_WinSim.c.
As suggested, because logging_stack.h and logging_levels.h are used not only by demos but also by platform-specific transport code, it would make sense to move FreeRTOS-Plus/Demos/Common/Logging to FreeRTOS-Plus/Source/Logging. The same is done for demo_logging.c and demo_logging.h, which are duplicated by several demos. Win32.vcxproj project files are also updated to follow suite.