How enable video flexfec-03 ?

[Igor Afanasiev]

Hello everyone! How I can enable flexfec-03 encoding for video rtp-to-webrtc stream?

I create offer
```      if (videoOffer) {
        //Create video media
        let video = new MediaInfo(videoOffer.getId(), "video");

        //Get codec types
        let h264 = videoOffer.getCodec("h264");
        let fec = videoOffer.getCodec("flexfec-03");
        //Add video codecs
        video.addCodec(h264);
        if (fec) {
          video.addCodec(fec);
        }
        //Set recv only
        video.setDirection(Direction.SENDONLY);
        //Add it to answer
        answer.addMedia(video);

        console.log("video info", video);
        for (let value of video.getCodecs().values()) {
          console.log("video codec info", value.params, value.rtcpfbs);
        }
      }
```

Get from logs support fec mechanism.

```video info MediaInfo {
  id: '1',
  type: 'video',
  direction: Symbol(MEDOOZE_SEMANTIC_SDP_SENDONLY),
  extensions: Map(0) {},
  codecs: Map(2) {
    102 => CodecInfo {
      codec: 'H264',
      type: 102,
      params: [Object],
      rtcpfbs: [Set],
      rtx: 103
    },
    49 => CodecInfo {
      codec: 'flexfec-03',
      type: 49,
      params: [Object],
      rtcpfbs: [Set]
    }
  },
  rids: Map(0) {},
  simulcast: null,
  bitrate: 0,
  control: null,
  dataChannel: null
}```
But in chrome://webrtc-internals/ I saw always 0 value for fecRecived graph
Please help!!!