Add support for new options: thumbnails, subtitles, metadata, etc.

[qx6ghqkz]

List of new environment variables which can be specified in a .env file before running docker compose up or can be passed via the -e flag when creating a container using docker run:

Environment Variable	Type	Default Value	Example
YDL_MERGE_OUTPUT_FORMAT	String	None	YDL_MERGE_OUTPUT_FORMAT="mp4/mkv"
YDL_NO_PLAYLIST	Boolean	True	YDL_NO_PLAYLIST=True
YDL_COOKIES_FILE	String	None	YDL_COOKIES_FILE="/data/cookies.txt"
YDL_COOKIES_BROWSER	String	None	YDL_COOKIES_BROWSER="firefox"
YDL_IGNORE_ERRORS	Boolean/String	True	YDL_IGNORE_ERRORS=True
YDL_RESTRICT_FILENAMES	Boolean	False	YDL_RESTRICT_FILENAMES=True
YDL_GEO_BYPASS	Boolean	False	YDL_GEO_BYPASS=True
YDL_WRITE_THUMBNAIL	Boolean	True	YDL_WRITE_THUMBNAIL=True
YDL_THUMBNAIL_FORMAT	String	None	YDL_THUMBNAIL_FORMAT="png/jpg"
YDL_WRITE_SUBTITLES	Boolean	False	YDL_WRITE_SUBTITLES=True
YDL_SUBTITLES_FORMAT	String	None	YDL_SUBTITLES_FORMAT="srt/vtt/best"
YDL_CONVERT_SUBTITLES	String	None	YDL_CONVERT_SUBTITLES="srt"
YDL_SUBTITLES_LANGS	String	"all"	YDL_SUBTITLES_LANGS="en.*,ja"
YDL_EMBED_METADATA	Boolean	False	YDL_EMBED_METADATA=True

Solves #29 and #33.

For more information on these options see yt-dlp/YoutubeDL.py.