Access existing I/O APIS using Pipelines

The UsePipeReader(), UsePipeWriter(), UsePipe() extension methods are offered on the following types:

1. Stream
2. WebSocket

By using these extension methods on these types, one can use efficient PipeReader and PipeWriter classes to perform I/O operations and connect these transports with APIs that use these.

Using these APIs isn't automatically better than the classic Stream.ReadAsync and Stream.WriteAsync methods, but can be very useful when writing code that interops with native memory or other pipeline APIs in order to avoid unnecessary buffer copies.

One can use these apis on System.Net.Sockets.Socket, by wrapping it in a System.Net.Sockets.NetworkStream

// 'Socket' has already been created and connected.
var networkStream = new NetworkStream(Socket, ownsSocket: false);
IDuplexPipe pipe = networkStream.UsePipe(cancellationToken: DisposedToken);