Adding UNICEF topics

[hn437]

Description

This PR adds the topics required for the UNICEF Project as described in issue #832 and implements the new project. All required updates as assignments of topics to the indicators or updating the relevant tests are done as well.

Corresponding issue

Closes #832

New or changed dependencies

Checklist

• I have updated my branch to main (e.g. through git rebase main)
• My code follows the style guide and was checked with pre-commit before committing
• I have commented my code
• I have added sufficient unit and integration tests
• I have updated the CHANGELOG.md

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[mmerdes]

checked by @Gigaszi and myself: metadata config looks consistent; tested with frontend as well.