Simplify using FFmpeg filters

[federicocarboni]

Description

Improve the API to include helpers to add filters. Both output filters and complex filters should be supported.
Related links:
https://ffmpeg.org/ffmpeg-filters.html

Examples

const cmd = ffmpeg();
cmd.output()
  .complexFilter('my_filter', /* options? */)
  .videoFilter('negate', /* options? */)
  .audioFilter('highpass', /* options? */);