Updates the UI to use the new API endpoints for tasks and use its new
data model.
Disclaimer: Since the base data model for tasks changed, we had to do a
quite large refactor and I'm sorry for that 🙏, but you'll notice most of
the changes are to adjust the types.
Closescoder/internal#976
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Co-authored-by: Bruno Quaresma <bruno_nonato_quaresma@hotmail.com>