Check whether the converted version of each legacy theme matches it sufficiently, so that we can switch production campaigns to the simpler new version and afterwards remove the legacy.

We need to check whether the intended styles (colors, spacings, font-sizes, text transforms) are all present.

If some customizations from the legacy theme are not in the new version, we can assess whether those things are really needed (e.g. small spacing changes). I think there's only a handful such cases, but maybe more will be spotted as we review.

If you want to make further changes to the theme, you can make one or more copies of it. To copy, just type a different name in the text field at the top, and click the "Upload" button next to it.

For now this can be done on the "test-nix" test instance. It currently already has climate, oceans, and plastics themes on it. Atm I still need to allow switching a campaign to the new themes outside of the editor. https://www-dev.greenpeace.org/test-nix/ I'll update this ticket with links to each campaign page.

Feel free to break this ticket up into a ticket per theme if that works better.

Documentation on theme editor usage: https://github.com/Inwerpsel/use-theme-editor/blob/main/docs/USAGE.md