Improve the editor props’ JSDoc annotations

[thibaudcolas]

This is in preparation for #429, and to improve the experience for setups that already offer some form of inference of props.

There should be no actual change to the props here – just adding annotations.

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• [x] Stay on point and keep it small so it can be easily reviewed. For example, try to apply any general refactoring separately outside of the PR.
• [ ] Consider adding unit tests, especially for bug fixes. If you don't, tell us why.
• [x] All new and existing tests pass, with 100% test coverage (npm run test:coverage)
• [x] Linting passes (npm run lint)
• [x] Consider updating documentation. If you don't, tell us why.
• [x] List the environments / platforms in which you tested your changes. Storybook only.

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