RTSPPusher write_header() gets blocked if rtsp server is not available

[Vinayak-YB]

Describe the bug
In processSOS of RTSPPusher we make a call to write_header() function which internally calls avformat_write_header with outContext. If the RTSP server is not available then the function does not return anything blocking the process. There are comments added below the avformat_write_header pointing to this issue.

To Reproduce
Steps to reproduce the behavior: Run RTSP Pusher tests without the rtsp server and observe behaviour in procesSOS function.

Solution:
Add an interrupt callback to outContext with timeout logic before calling avformat_write_header(). Please find the associated code below. We need to add test cases for this scenario in rtsppusher_tests.

typedef struct 
{
    AVFormatContext* formatContext;
    int timeout_ms;       
    uint64_t start_time_ms;    
} InterruptCallbackData;

static int rtspInterruptCallback(void *ctx) 
{
      LOG_TRACE<<"Callback triggered";
      InterruptCallbackData* callbackData = reinterpret_cast<InterruptCallbackData*>(ctx);
      std::chrono::time_point<std::chrono::system_clock> t = std::chrono::system_clock::now();
      auto dur = std::chrono::duration_cast<std::chrono::milliseconds>(t.time_since_epoch());
      uint64_t current_time = dur.count();
      if ((current_time - callbackData->start_time_ms) > callbackData->timeout_ms) 
      {
          LOG_INFO<<"Timeout reached in callback, returning error";
          return -1; 
      }
      return 0; 
}

//Interrupt callback 
InterruptCallbackData callbackData;
callbackData.formatContext = outContext;
callbackData.timeout_ms = rtspTimeout;  //This value is passed as props for rtspPusher module
std::chrono::time_point<std::chrono::system_clock> t = std::chrono::system_clock::now();
auto dur = std::chrono::duration_cast<std::chrono::milliseconds>(t.time_since_epoch());
uint64_t now = dur.count();
callbackData.start_time_ms = now; 
outContext->interrupt_callback.callback = rtspInterruptCallback;
outContext->interrupt_callback.opaque = &callbackData;
outContext->flags = outContext->flags | AVFMT_FLAG_NONBLOCK;
ret = avformat_write_header(outContext, &options);