relaxing manifest creation

[Eldies]

Motivation and context

After update of ffmpeg, for some videos, when seeking to a keyframe, seek lands on a previous keyframe.

With our current way of creating manifest, for such videos the manifest is empty.
It is not optimal: it is a lot better to be able to seek to 1000th keyframe of some video and land on 999th keyframe and decode to 1000th, than to decode all the way from video beginning.

Relaxing manifest creation for such cases.

How has this been tested?

Checklist

• I submit my changes into the develop branch
• I have created a changelog fragment
• I have updated the documentation accordingly
• I have added tests to cover my changes
• I have linked related issues (see GitHub docs)

License

• I submit my code changes under the same MIT License that covers the project.
  Feel free to contact the maintainers if that's a concern.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 83.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.89%. Comparing base (56a4d22) to head (d61b663).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #9994      +/-   ##
===========================================
- Coverage    82.58%   73.89%   -8.69%     
===========================================
  Files          484      428      -56     
  Lines        49339    46249    -3090     
  Branches      4134     4134              
===========================================
- Hits         40745    34175    -6570     
- Misses        8594    12074    +3480     

Components	Coverage Δ
cvat-ui	77.62% <ø> (+0.12%)	⬆️
cvat-server	70.73% <83.33%> (-15.68%)	⬇️

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[SpecLad]

Please add a changelog entry.

[Eldies]

Please add a changelog entry.

done

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud