TUN-4597: Add a QUIC server skeleton

- Added a QUIC server to accept streams
- Unit test for this server also tests ALPN
- Temporary echo capability for HTTP ConnectionType

vendor/github.com/lucas-clemente/quic-go/internal/protocol/perspective.go

@@ -0,0 +1,26 @@
+package protocol
+
+// Perspective determines if we're acting as a server or a client
+type Perspective int
+
+// the perspectives
+const (
+	PerspectiveServer Perspective = 1
+	PerspectiveClient Perspective = 2
+)
+
+// Opposite returns the perspective of the peer
+func (p Perspective) Opposite() Perspective {
+	return 3 - p
+}
+
+func (p Perspective) String() string {
+	switch p {
+	case PerspectiveServer:
+		return "Server"
+	case PerspectiveClient:
+		return "Client"
+	default:
+		return "invalid perspective"
+	}
+}