Added tests for Http2Middleware

* Added unit tests for middleware
* Message handling code

src/Stream/Http2Stream.php

@@ -10,6 +10,7 @@ use NoccyLabs\React\Http2\Connection\Http2Connection;
  *
  * 
  */
+// TODO add DuplexStreamInterface here
 class Http2Stream
 {
     const STATE_IDLE = 0;
@@ -22,6 +23,13 @@ class Http2Stream
 
     private int $state = self::STATE_IDLE;
 
+    private int $index;
+
     private Http2Connection $connection;
 
-}
+    public function __construct(Http2Connection $connection, int $index)
+    {
+
+    }
+
+}