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/handshake/hkdf.go

@@ -0,0 +1,29 @@
+package handshake
+
+import (
+	"crypto"
+	"encoding/binary"
+
+	"golang.org/x/crypto/hkdf"
+)
+
+// hkdfExpandLabel HKDF expands a label.
+// Since this implementation avoids using a cryptobyte.Builder, it is about 15% faster than the
+// hkdfExpandLabel in the standard library.
+func hkdfExpandLabel(hash crypto.Hash, secret, context []byte, label string, length int) []byte {
+	b := make([]byte, 3, 3+6+len(label)+1+len(context))
+	binary.BigEndian.PutUint16(b, uint16(length))
+	b[2] = uint8(6 + len(label))
+	b = append(b, []byte("tls13 ")...)
+	b = append(b, []byte(label)...)
+	b = b[:3+6+len(label)+1]
+	b[3+6+len(label)] = uint8(len(context))
+	b = append(b, context...)
+
+	out := make([]byte, length)
+	n, err := hkdf.Expand(hash.New, secret, b).Read(out)
+	if err != nil || n != length {
+		panic("quic: HKDF-Expand-Label invocation failed unexpectedly")
+	}
+	return out
+}