Enable Simple Taxonomy Import

I think I've finally figured out how to expand entity relationships in our bundle schemas. I've overridden web/modules/contrib/schemata/schemata_json_schema/src/Normalizer/jsonapi/RelationshipFieldDefinitionNormalizer.php for entity relationships that start with "field_".

A potential issue is that it is recursive, so it could lead to a very large schema -- or perhaps an infinite loop if there is a circular reference.

I also still need to fix up normalizeResponse() in AiMigrator so that it doesn't normalize out the relationships in the AI response.

We should also build in some sort of filter in the migration yml so that we only add fields that are relevant to the schema.

Here is a sample of the schema Drupal is building right now.

Finally have an MR for this: https://git.drupalcode.org/project/ai_migration/-/merge_requests/27.

QA Steps:

1. ddev poser
2. ddev drush cr
3. Roll back any previous migrations of the complex_content_migration type.
4. ddev drush migrate:rollback complex_content_migration
5. If you do not have any terms in the Subjects taxonomy, add these (capitalization matters!):
   • Fiction
   • Science fiction
6. In your terminal, run ddev drush migrate:import complex_content_migration
7. Confirm there are not any errors (crossing fingers). However, you will likely see a warning, which will be dealt with in another ticket: [warning] Referenced entity not found: taxonomy_term--subjects.
8. Go to the content list and confirm that you have 2 new entries:
   • The Martian Chronicles
   • The Time Machine
9. Click on Edit next to each entry.
10. Confirm that each entry has 2 entries for Subjects:
    • Fiction
    • Science fiction

@dmundra -- thx for testing and fixing up the tests. I had forgotten to mention adding the taxonomy terms. Do you think we should add an install hook to add those? We don't have instructions dedicated to the ai_migration_example module. We could add directions there, but my guess is that they will be missed. Thoughts?

@dmundra thx for adding in the taxonomy import!

It works for me when I install the ai_migration_example module from scratch.

With the module already enabled (and taxonomy deleted), I can't get it to work correctly.

Steps:
1. $ ddev drush cr
2. $ ddev drush updb
[success] No pending updates.
3. $ ddev drush config-import --partial --source=modules/custom/ai_migration/modules/ai_migration_example/config/optional

+------------+-----------------------------------------------------------+-----------+
| Collection | Config                                                    | Operation |
+------------+-----------------------------------------------------------+-----------+
|            | node.type.complex_content_migration                       | Update    |
|            | field.field.node.complex_content_migration.field_subjects | Update    |
+------------+-----------------------------------------------------------+-----------+

 ┌ Import the listed configuration changes? ────────────────────┐
 │ Yes                                                          │
 └──────────────────────────────────────────────────────────────┘


In ConfigImportCommands.php line 291:
                                                                                                                                                                                                                                 
  The import failed due to the following reasons:                                                                                                                                                                                
  Configuration <em class="placeholder">field.field.node.complex_content_migration.field_subjects</em> depends on the <em class="placeholder">taxonomy.vocabulary.subjects</em> configuration that will not exist after import.  

It looks like updb does not running the post_update hook for some reason. I tried to see if it was already run, and it looks like it wasn't:

$ ddev drush state:get system.post_update

$

This isn't a use case I'm too concerned about, but there may be a couple people out there who will need to update their locals (including other devs on this project).

So, maybe give it a look?

Something else I had a question about -- why move the subject taxonomy to config/install? If it's in config/optional, there's no error thrown if you already have the taxonomy (which I sometimes do, for instance).