Windows async networking

[Sashiri]

• Ignores unknown errors in windows GetQueuedCompletionStatus logic
• Adds kernel32.GetFileType function and FileType enum, for fd checking
• Adds WSA_FLAG_OVERLAPPED to socket if requesting SOCK.NONBLOCK in windows
• Adds listening socket to IOCP if io_mode is .evented
• Fixes windows WriteFile and ReadFile for sockets, by ignoring offset and SetFilePointerEx calls if fd is a pipe device
• Adds and calls windows.acceptEx from os.accept if io_mode is .evented

[gajanak]

@Sashiri #10115

Thanks.. i dont found your branch/PR - and implement it (first-try experimental) in the same way by myself.
I know this works, with current Loop design. Where was your show stopper ?
Wouldn't it a alternative to get this in std, to get working NetServer on windows if io_mode=.eventd until Loop is redesigned later?
But I used WSARecv and WSASend For networki IO, dont try to get file and network the same IO, which is sadly not the windows-way. I don't change ReadFile and WriteFile , removing complexity.

[Sashiri]

I was unhappy with the quality and possible future maintenance of code, for example GetQueuedCompletionStatus ignoring all errors which could be considered an antipattern for the current design of std. There're also multiple assumptions of socket and connection proto