Datahub: Display search filter topic label in plural

[tkohr]

Description

This PR introduces proposes to change topic to topics in the search filter labels (just like formats). It might be worth discussing if we should display all search filter labels rather in plural or singular.

Also adds a small refinement on the geo badge.

Screenshot

Quality Assurance Checklist

• Commit history is devoid of any merge commits and readable to facilitate reviews
• If new logic ⚙️ is introduced: unit tests were added
• If new user stories 🤏 are introduced: E2E tests were added
• If new UI components 🕹️ are introduced: corresponding stories in Storybook were created
• If breaking changes 🪚 are introduced: add the breaking change label
• If bugs 🐞 are fixed: add the backport <release branch> label
• The documentation website 📚 has received the love it deserves

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This work is sponsored by geo2france.

[github-actions]

Affected libs: ``,
Affected apps: datahub,

• 🚀 Build and deploy storybook and demo on GitHub Pages
• 📦 Build and push affected docker images

[coveralls]

coverage: 82.903% (+1.9%) from 80.977%
when pulling 09e8c72 on dh-css-and-translations
into a1bcfe2 on main.

[github-actions]

📷 Screenshots are here!

[jahow]

thanks!!