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/crypto_stream_manager.go

@@ -0,0 +1,61 @@
+package quic
+
+import (
+	"fmt"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/wire"
+)
+
+type cryptoDataHandler interface {
+	HandleMessage([]byte, protocol.EncryptionLevel) bool
+}
+
+type cryptoStreamManager struct {
+	cryptoHandler cryptoDataHandler
+
+	initialStream   cryptoStream
+	handshakeStream cryptoStream
+	oneRTTStream    cryptoStream
+}
+
+func newCryptoStreamManager(
+	cryptoHandler cryptoDataHandler,
+	initialStream cryptoStream,
+	handshakeStream cryptoStream,
+	oneRTTStream cryptoStream,
+) *cryptoStreamManager {
+	return &cryptoStreamManager{
+		cryptoHandler:   cryptoHandler,
+		initialStream:   initialStream,
+		handshakeStream: handshakeStream,
+		oneRTTStream:    oneRTTStream,
+	}
+}
+
+func (m *cryptoStreamManager) HandleCryptoFrame(frame *wire.CryptoFrame, encLevel protocol.EncryptionLevel) (bool /* encryption level changed */, error) {
+	var str cryptoStream
+	//nolint:exhaustive // CRYPTO frames cannot be sent in 0-RTT packets.
+	switch encLevel {
+	case protocol.EncryptionInitial:
+		str = m.initialStream
+	case protocol.EncryptionHandshake:
+		str = m.handshakeStream
+	case protocol.Encryption1RTT:
+		str = m.oneRTTStream
+	default:
+		return false, fmt.Errorf("received CRYPTO frame with unexpected encryption level: %s", encLevel)
+	}
+	if err := str.HandleCryptoFrame(frame); err != nil {
+		return false, err
+	}
+	for {
+		data := str.GetCryptoData()
+		if data == nil {
+			return false, nil
+		}
+		if encLevelFinished := m.cryptoHandler.HandleMessage(data, encLevel); encLevelFinished {
+			return true, str.Finish()
+		}
+	}
+}