Csv export import

[TimoBroeskamp]

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• I verified there aren't other open pull requests for the same change.
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• I successfully ran code linting checks on my changes locally.
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If your pull request closes an open issue, include the exact text below, immediately followed by the issue number. When your pull request gets merged, then that issue will close automatically.

Closes #8356

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The UI of this prototype is not final and I am open for any recomendations on how to build it more intuitively.

[TimoBroeskamp]

The Unis tests fail because I added another element to the dom that the test checks for changes.

These are images of my prototype:

As you can see there is a "Download CSV" button and a fourth option in the toolbar tu upload users that opens the dropzone.

[read-the-docs-community]

Documentation build overview

📚 volto | 🛠️ Build #34240739 | 📁 Comparing 7beb8b8 against latest (cfeb611)

  🔍 Preview build  

4 files changed

± backend/index.html
± contributing/typescript.html
± upgrade-guide/index.html
± development/add-ons/create-an-add-on-18.html