fix(convert): avoid micro-stuttering with --one-file in HTML presentation

[Rapsssito]

Description

As described in hakimel/reveal.js#3362 (reply in thread), currently, the base64 representation of the slide is loaded "on the fly" by RevealJS, which in results in a few frames of a blank screen. This solution is only executed once and updates all videos "src" attribute at the beginning of the presentation.

Check List

Check all the applicable boxes:

• I understand that my contributions needs to pass the checks;
• If I created new functions / methods, I documented them and add type hints;
• If I modified already existing code, I updated the documentation accordingly;
• The title of my pull request is a short description of the requested changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.56%. Comparing base (478552c) to head (5ddc945).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #508   +/-   ##
=======================================
  Coverage   79.56%   79.56%           
=======================================
  Files          23       23           
  Lines        1962     1962           
=======================================
  Hits         1561     1561           
  Misses        401      401           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[Rapsssito]

@jeertmans, I am not sure if I should also update the docs/source/_static/template.html file...

[jeertmans]

Hi @Rapsssito, thanks for your PR!

@jeertmans, I am not sure if I should also update the docs/source/_static/template.html file...

Yes, please :)

[Rapsssito]

Done!

[jeertmans]

Thanks, @Rapsssito! Can you just add an entry to the CHANGELOG, in Changed?

[Rapsssito]

Done!

[jeertmans]

Thanks for your contribution @Rapsssito!