feat: render html meta tags in Django, with video metadata for entity pages

[amatissart]

Description

More extensive implementation of OpenGraph meta tags, as an alternative to current tags injected by Nginx

For direct urls about videos (/entities/<uid>), the tags will contain some metadata about the video:

• "og:title" is the title of the video
• "og:description" is the name of the YouTube channel
• "og:video:url" is the URL of the embedded YouTube, although I could not find a service where the player is shown. Platforms like Bluesky which allow to play videos, seem to rely on a shortlist of accepted external media.

Preview on Discord:

Preview on Bluesky:

Checklist

• I added the related issue(s) id in the related issues section (if any)
  • if not, delete the related issues section
• I described my changes and my decisions in the PR description
• I read the development guidelines of the CONTRIBUTING.md
• The tests pass and have been updated if relevant
• The code quality check pass