Add subtitle files with metadata specified from the CLI

#!/usr/bin/env bash
ffmpeg -i video.mp4 -i RU.srt -i EN.srt -c:v copy -c:a copy -c:s mov_text \
    -map 0 -dn -map "-0:s" -map "-0:d" \
    -map "1:0" "-metadata:s:s:0" "language=RU" "-metadata:s:s:0" "handler_name=Russian"  "-metadata:s:s:0" "title=Russian" \
    -map "2:0" "-metadata:s:s:1" "language=EN" "-metadata:s:s:1" "handler_name=English" "-metadata:s:s:1" "title=English" \
    -f mp4 video_sub.mp4