ffmpegextractor: extract video and audio codec, pixel format and color space

Example:

LANG=en ./bin/kfilemetadata_dump6 video.mkv
                [...]
                Video Codec: h264 (QString)
                Audio Codec: aac (QString)
                Pixel Format: yuv420p (QString)
                Color Space: unknown (QString)
        -------------

Color Space property added for video only. Likewise for audio codec.

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Color Space and pixel format property can be later added to image formats, currently not implemented. Likewise for audio codec, only supported for videos.

Suggested by https://discuss.kde.org/t/rich-media-info-in-dolphin-or-a-dedicated-app/31322/4