[data-viz] Streamlit: Added users growth graph (#1726)

[NatNgs]

related issues #1726

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Add user-growth plot in Tournesol's streamlit app

Added a new plot in Streamlit, displaying the number of contributors, new users and active users in one line plot.

"Active" users are defined as having done at least one comparison on the week or before, and having done at least one comparison on the week or after.

Checklist

• [x] I added the related issue(s) id in the related issues section (if any)
• [x] I described my changes and my decisions in the PR description
• [x] I read the development guidelines of the CONTRIBUTING.md
• [x] The tests pass and have been updated if relevant
• [ ] The code quality check pass

❤️ Thank you for your contribution!