Deprecated createEventDispatcher usage in Svelte components

[leedoughty]

The codebase currently uses createEventDispatcher (example usage here), which is deprecated in Svelte 5.

The Svelte 5 migration guide recommends using callback props instead of dispatching events. It may be worth refactoring affected components to follow the new pattern and maintain forward compatibility with Svelte 5.

[abdnh]

Would be nice to fully migrate to Svelte 5 along the way, but it's a larger task.

[AmandaSternberg-creator]

I would like to help out with this issue in Svelte. I was thinking I could start by refactoring a few components to use callback props instead, or is that a non go since you want to try to do everything at once? :)

[abdnh]

I could start by refactoring a few components to use callback props instead, or is that a non go since you want to try to do everything at once? :)

I personally think that's fine, but you might want to wait for Damien's opinion before spending time on it. Also, this is likely to conflict with changes in #4029 and #4289 so might be better done after the PRs are merged.