Spring-ai Fixed Azure Vector Store initialization where the embedding field was not set as Retrievable.

In Azure Vector Store, the embedding field need to set as retrievable. com.azure.search.documents.indexes.models.SearchField class does not have a retrievable field, but the "hidden" field is equivalent to "retrievable". For details, refer to the "toJson" and "fromJson" methods.

fix https://github.com/spring-projects/spring-ai/issues/1628

Comment From: sobychacko

Closing via https://github.com/spring-projects/spring-ai/commit/382fbaca48448caeaddf78f5fc7bed83c52ed90c.