Necessary for #343.
* They are identified by `vcodec=acodec='none'`
* These formats show as the worst in `-F`
* Any postprocessor that expects audio/video will be skipped
* `b*` and all related selectors will skip such formats
* This commit also does not add any selector for downloading such formats. They have to be explicitly requested by the `format_id`. Implementation of a selector is left for when #389 is resolved
* Create `FFmpegPostProcessor.real_run_ffmpeg` that can accept multiple input/output files along with switches for each
* Rewrite `cli_configuration_args` and related functions
* Create `YoutubeDL._ensure_dir_exists` - this was previously defined in multiple places
* All modules and binary names are changed
* All documentation references changed
* yt-dlp no longer loads youtube-dlc config files
* All URLs changed to point to organization account
Co-authored-by: Pccode66
Co-authored-by: pukkandan
pukkandan