[Feature Request] add NotifyOnProgress for FFMpeg.Join

[zhangqi-ulua]

Now, FFMpeg.Join only return bool result, we can't know progress and ffmpeg warn and error info

[clazarev]

Hi, i just found your question, I think It makes sense to me that FFMpeg.* is just a quick helper and is not overpolluted with optional parameters
You can always check what a method does, and use its body in your code

 return FFMpegArguments
                .FromConcatInput(temporaryVideoParts)
                .OutputToFile(output, true, options => options
                    .CopyChannel()
                    .WithBitStreamFilter(Channel.Audio, Filter.Aac_AdtstoAsc))
                .NotifyOnProgress(progress =>
                {
                    // Console.WriteLine($"Joining videos: {progress}%");
                })
                .ProcessSynchronously();