improve subtitle lang, retry, debugging & error handling

[tonymet]

What this Pull Request (PR) does

Improve yt-dlp stability & debugging to address #1787 & #1785

• simplify retry / no-lang routine to preserve --yt-dlp-args and other args
• output yt-dlp args, stdout & stderr when --debug=3 is passed
• fix bug with --sub-langs redundant lang (red herring)

Related issues

#1787 -- fixed by reducing side-effects with args & --yt-dlp-args
#1785 -- partially fixed by improving debugging and passthrough of --yt-dlp-args=--sleep-requests 1"

Screenshots

example debug output showing args , stdout + stderr from yt-dlp

DEBUG: yt-dlp [yt-dlp --write-auto-subs --skip-download --sub-format vtt -o C:\Users\tonymet\AppData\Local\Temp\fabric-youtube-LGd6GXq7L2Y\%(title)s.%(ext)s --sub-langs en,en.* --sleep-requests 1 https://www.youtube.com/watch?v=LGd6GXq7L2Y]
DEBUG: [youtube] Extracting URL: https://www.youtube.com/watch?v=LGd6GXq7L2Y
DEBUG: [youtube] LGd6GXq7L2Y: Downloading webpage
DEBUG: [youtube] Sleeping 1.0 seconds ...
DEBUG: [youtube] LGd6GXq7L2Y: Downloading tv client config
DEBUG: [youtube] Sleeping 1.0 seconds ...
DEBUG: [youtube] LGd6GXq7L2Y: Downloading tv player API JSON
DEBUG: [youtube] Sleeping 1.0 seconds ...
DEBUG: [youtube] LGd6GXq7L2Y: Downloading web safari player API JSON
DEBUG: [youtube] Sleeping 1.0 seconds ...
DEBUG: [youtube] LGd6GXq7L2Y: Downloading m3u8 information
DEBUG: [info] LGd6GXq7L2Y: Downloading subtitles: en, en-orig
DEBUG: [info] LGd6GXq7L2Y: Downloading 1 format(s): 315+251
DEBUG: [info] Writing video subtitles to: C:\Users\tonymet\AppData\Local\Temp\fabric-youtube-LGd6GXq7L2Y\Finding the Best 1 Gallon Keg for Homebrewing & Giving It Away!.en.vtt
DEBUG: [download] Destination: C:\Users\tonymet\AppData\Local\Temp\fabric-youtube-LGd6GXq7L2Y\Finding the Best 1 Gallon Keg for Homebrewing & Giving It Away!.en.vtt
[download] 100% of  153.21KiB in 00:00:00 at 708.00KiB/s
DEBUG: [info] Writing video subtitles to: C:\Users\tonymet\AppData\Local\Temp\fabric-youtube-LGd6GXq7L2Y\Finding the Best 1 Gallon Keg for Homebrewing & Giving It Away!.en-orig.vtt
DEBUG: [download] Destination: C:\Users\tonymet\AppData\Local\Temp\fabric-youtube-LGd6GXq7L2Y\Finding the Best 1 Gallon Keg for Homebrewing & Giving It Away!.en-orig.vtt
[download] 100% of  153.21KiB in 00:00:00 at 941.82KiB/s

Retry Example

DEBUG: yt-dlp [yt-dlp --write-auto-subs --skip-download --sub-format vtt -o C:\Users\tonymet\AppData\Local\Temp\fabric-youtube-LGd6GXq7L2Y\%(title)s.%(ext)s --sub-langs zzz,zz.*,zz --sleep-requests 1 https://www.youtube.com/watch?v=LGd6GXq7L2Y]
[TRUNCATED]
DEBUG: yt-dlp [yt-dlp --write-auto-subs --skip-download --sub-format vtt -o C:\Users\tonymet\AppData\Local\Temp\fabric-youtube-LGd6GXq7L2Y\%(title)s.%(ext)s --sleep-requests 1 https://www.youtube.com/watch?v=LGd6GXq7L2Y]      
[TRUNCATED]
DEBUG: Starting template processing
DEBUG: Starting template processing

Testing

Test the retry with these args

# set lang to zzz to force retry
 ["-g", "zzz", "--debug=3", "-y", "https://www.youtube.com/watch?v=LGd6GXq7L2Y", "-p", "extract_wisdom", "--yt-dlp-args=--sleep-requests 1"],

[ksylvan]

Cleaned some stuff up, and approved.

[tonymet]

great partnership as always. thanks @ksylvan