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/congestion/interface.go

@@ -0,0 +1,28 @@
+package congestion
+
+import (
+	"time"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+)
+
+// A SendAlgorithm performs congestion control
+type SendAlgorithm interface {
+	TimeUntilSend(bytesInFlight protocol.ByteCount) time.Time
+	HasPacingBudget() bool
+	OnPacketSent(sentTime time.Time, bytesInFlight protocol.ByteCount, packetNumber protocol.PacketNumber, bytes protocol.ByteCount, isRetransmittable bool)
+	CanSend(bytesInFlight protocol.ByteCount) bool
+	MaybeExitSlowStart()
+	OnPacketAcked(number protocol.PacketNumber, ackedBytes protocol.ByteCount, priorInFlight protocol.ByteCount, eventTime time.Time)
+	OnPacketLost(number protocol.PacketNumber, lostBytes protocol.ByteCount, priorInFlight protocol.ByteCount)
+	OnRetransmissionTimeout(packetsRetransmitted bool)
+	SetMaxDatagramSize(protocol.ByteCount)
+}
+
+// A SendAlgorithmWithDebugInfos is a SendAlgorithm that exposes some debug infos
+type SendAlgorithmWithDebugInfos interface {
+	SendAlgorithm
+	InSlowStart() bool
+	InRecovery() bool
+	GetCongestionWindow() protocol.ByteCount
+}