message: Remove unused isUnidirectionalStream() function
diff: @@ -50,13 +50,6 @@ quic::PacketNum nextAckedPacketLen(
  return packetNum - ackBlockLen;
  }
  -/**
  - * Returns whether the given StreamId identifies a unidirectional stream.
  - */
  -bool isUnidirectionalStream(quic::StreamId stream) {
  - return stream & 0b10;
  -}
  -
  // The octet following the version contains the lengths of the two connection ID
  // fields that follow it
  constexpr size_t kConnIdLengthOctet = 1;
  