Add CreatePipe extension method for WebSocket

This makes the API slightly more discoverable.

Fixes #8

Author: kzu

src/Tests/EndToEnd.cs

@@ -16,7 +16,7 @@ public async Task RunAsync()
         var client = new ClientWebSocket();
 
         await client.ConnectAsync(server.Uri, CancellationToken.None);
-        using var pipe = WebSocketPipe.Create(client, closeWhenCompleted: true);
+        using var pipe = client.CreatePipe(closeWhenCompleted: true);
 
         var read = Task.Run(async () =>
         {

src/WebSocketPipe/WebSocketExtensions.cs

@@ -0,0 +1,26 @@
+using System.ComponentModel;
+using System.IO.Pipelines;
+using Devlooped.Net;
+
+namespace System.Net.WebSockets;
+
+/// <summary>
+/// Provides the <see cref="CreatePipe"/> extension method for 
+/// reading/writing to a <see cref="WebSocket"/> using the <see cref="IDuplexPipe"/> (and 
+/// <see cref="IWebSocketPipe"/>) API.
+/// API.
+/// </summary>
+[EditorBrowsable(EditorBrowsableState.Never)]
+public static class WebSocketExtensions
+{
+    /// <summary>
+    /// Creates a <see cref="IWebSocketPipe"/> over the given <paramref name="webSocket"/>.
+    /// </summary>
+    /// <param name="webSocket">The <see cref="WebSocket"/> to adapt.</param>
+    /// <param name="closeWhenCompleted">Whether to close the <paramref name="webSocket"/> when 
+    /// either the <see cref="IDuplexPipe.Input"/> or <see cref="IDuplexPipe.Output"/> is 
+    /// completed, or when <see cref="IWebSocketPipe.CompleteAsync"/> is invoked.</param>
+    public static IWebSocketPipe CreatePipe(this WebSocket webSocket, bool closeWhenCompleted = false)
+        => WebSocketPipe.Create(webSocket, closeWhenCompleted ? new WebSocketPipeOptions { CloseWhenCompleted = true } : WebSocketPipeOptions.Default);
+}
+