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/conn_helper_linux.go

@@ -0,0 +1,17 @@
+// +build linux
+
+package quic
+
+import "golang.org/x/sys/unix"
+
+const msgTypeIPTOS = unix.IP_TOS
+
+const (
+	ipv4RECVPKTINFO = unix.IP_PKTINFO
+	ipv6RECVPKTINFO = unix.IPV6_RECVPKTINFO
+)
+
+const (
+	msgTypeIPv4PKTINFO = unix.IP_PKTINFO
+	msgTypeIPv6PKTINFO = unix.IPV6_PKTINFO
+)