[Developer Feedback required] FFMPEG prevent hls stream segment loss; command arguments

[Kronos]

Issue:
JDownloader uses ffmpeg to download hls streams. If ffmpeg encounters any issue with a segment, it will immediately skip the segment and continue without error. The final file will look complete, but segments can be missing.

Useful for:
Everyone using ffmpeg plugin for download. Client and server location and connection quality plays a huge role how often this is an issue.

Suggestions:
- add expert options for ffmpeg hls command arguments; right now arguments can be changed for muxing, but not hls download (see **External links are only visible to Support Staff****External links are only visible to Support Staff**)
- maybe add ffmpeg option "-seg_max_retry X"; this is a relatively new argument that will retry failed segments X times (see **External links are only visible to Support Staff****External links are only visible to Support Staff**)
- optionally fail download, if segments have been skipped (don't fail on default, often actual live streams cannot be redownloaded)
- allow custom command line arguments per download; something like #forced_referer which is used in other plugins (see **External links are only visible to Support Staff****External links are only visible to Support Staff** specifically I am interested in setting -referer -user_agent -headers and -cookies (see **External links are only visible to Support Staff****External links are only visible to Support Staff**)

Sample output from ffmpeg with missing segments; this does not fail or stop the download:
[hls @ 00000266fc4b9e40] Opening '**External links are only visible to Support Staff** for reading
[https @ 00000266fe7b9cc0] HTTP error 404 Not Found
[hls @ 00000266fc4b9e40] Failed to open segment 193 of playlist 0
[hls @ 00000266fc4b9e40] Opening '**External links are only visible to Support Staff** for reading
[https @ 00000266fe7b9e80] HTTP error 404 Not Found
[hls @ 00000266fc4b9e40] Failed to open segment 194 of playlist 0