Add parameter to set startInfo.WorkingDirectory

[SunSerega]

I need to execute this command:

ffmpeg -dump_attachment:t "" -i {file}

If I specify anything other than "" as a path - the ffmpeg is going to try and (fail to) save all attachments into the same file.
And %d doesn't seem to be supported here...
The best solution I found is to set the working dir to a new empty folder, so as to not mix the output of this command with other files. But there doesn't seem to be functionality for that in xFFmpeg.Net rn - I don't see startInfo.WorkingDirectory being set anywhere.

[cmxl]

There is now an overload for ExecuteAsync where you can pass a workingdirectory.
I will actually consider to make ExecuteAsync with the FFmpegParameters public so it is easier to add further properties to the arguments.