Packaging field is too media specific

[wilaw]

Currently we have a track attribute called "packaging" which has two allowable values - "loc" and "cmaf". These are very media specific. We have many uses for tracks (transmitting different data types other than audio and video, such as game instructons, position, timeline data) with many different formatting options.

Suggestion is to remove the "packaging" field and its defined enumerations and replace it with a "Format" field of type String. We may want to define a max length. The allowed contents of the "format" field would be defined by the relevant application specification.

"tracks":[
    {
      "name": "game-instructions",
      "type": "datachannel",
      "format": "CBOR-special"
    },
    {
      "name": "media-timeline",
      "type": "timeline",
      "format": "csv"
    },
    {
      "name": "hd",
      "selectionParams": {"codec":"av01","width":1920,"height":1080,
      "bitrate":5000000,"framerate":30},
      "altGroup":1,
      "format": "cmaf"
    },
    {
      "name": "sd",
      "selectionParams": {"codec":"av01","width":192,"height":144,
      "bitrate":500000,"framerate":30},
      "altGroup":1,
      "format": "cmaf"
    },
    {
      "name": "audio",
      "selectionParams":{"codec":"opus","samplerate":48000,"channelConfig":"2",
      "bitrate":32000},
      "format": "loc"
    }
   ]