【Cicadaplayer】Conditional wait (wait) of avpkt queue (mPacketQueue)

• At this time, the network packet is read,
• Network packages may have audio, video, subtitles, etc.
• MAX_QUEUE_SIZE is the upper limit of the total number of packets, ensuring that mPacketQueue cannot be too large or too small.
• Less than this value, the reading thread will wait.
• The usage of std::condition_variable.wait() and the pitfalls caused by design flaws have been deeply analyzed by the master.

int avFormatDemuxer::readLoop() loops to read network packets

    std::unique_ptr<IAFPacket> pkt{
   
    
    };
    int ret = ReadPacketInternal(pkt)