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/golang.org/x/net/internal/socket/socket.go

@@ -90,17 +90,9 @@ func (o *Option) SetInt(c *Conn, v int) error {
 	return o.set(c, b)
 }
 
-func controlHeaderLen() int {
-	return roundup(sizeofCmsghdr)
-}
-
-func controlMessageLen(dataLen int) int {
-	return roundup(sizeofCmsghdr) + dataLen
-}
-
 // ControlMessageSpace returns the whole length of control message.
 func ControlMessageSpace(dataLen int) int {
-	return roundup(sizeofCmsghdr) + roundup(dataLen)
+	return controlMessageSpace(dataLen)
 }
 
 // A ControlMessage represents the head message in a stream of control