Broken support for FFMPEG for OpenCV with Nvidia Docker

@DaneLLL

I retested with script for building OpenCV 4.6, because script for 4.8 is broken: Unable to build OpenCV with CUDA in Docker on Jetson - #13 by pkot

And there is still lack of FFMPEG

-- Checking for modules 'libavcodec;libavformat;libavutil;libswscale'
--   Found libavcodec, version 58.54.100
--   Found libavformat, version 58.29.100
--   Found libavutil, version 56.31.100
--   Found libswscale, version 5.5.100
-- Checking for module 'libavresample'
--   No package 'libavresample' found
-- WARNING: Can't build ffmpeg test code
-- Checking for module 'gstreamer-base-1.0'
--   Video I/O:
--     DC1394:                      YES (2.2.5)
--     FFMPEG:                      NO
--       avcodec:                   YES (58.54.100)
--       avformat:                  YES (58.29.100)
--       avutil:                    YES (56.31.100)
--       swscale:                   YES (5.5.100)
--       avresample:                NO