Prepare for updated add fields to index UI

Probably better as 'Postponed' but setting to needs review as it would be good to get this reviewed and ready to go prior to ✨ Improve the Search API admin UI for adding/editing fields Active merge.

Composer failure is unrelated to this

Looks like composer failure is related to 📌 Automated Drupal 11 compatibility fixes for facets Active which is the case because this module has a dependency on facets.

This patch break the entire functionality of "Add new Solr Document fields".
The purpose of that feature is to filter the down the normal "Add field" modal to only offer fields that aren't configured yet.
This feature is entirely removed by the merge request.

To test it, you need a "foreign" Solr index not reflecting Drupal's data. By "adding" fields to the Search API Index you make that data available to be searched within Drupal and to build Views based on that data.

Fixed as per discussion in Slack; thank you for helping me reproduce the error and understand the purpose. I added a comment to the MR to explain the purpose here for future travellers.

Note that you need to update to the latest MR in ✨ Improve the Search API admin UI for adding/editing fields Active if you are rechecking.

Thank you!

Automatically closed - issue fixed for 2 weeks with no activity.