## Motivation
To solve: SWDEV-566076
FFmpeg versions >= 58.134 no longer expose read_seek and read_seek2 function pointers in AVInputFormat,
requiring alternative seek detection methods. This pull request updates the `VideoDemuxer` class to improve compatibility with newer versions of FFmpeg. The main change is how the code determines whether the input file is seekable, addressing differences in FFmpeg API versions.
## Technical Details
In `video_demuxer.h`, added a conditional check for `USE_AVCODEC_GREATER_THAN_58_134` to set `is_seekable_` to `true` for newer FFmpeg versions, since `read_seek` and `read_seek2` are no longer exposed in `AVFormatContext`. For older versions, the previous method of checking these fields remains in place. The conditional compilation
now assumes seek capability is available for newer FFmpeg versions.
anujshuk-amd
David Galiffi
Sajina PK