Do not recreate Meilisearch index if the primary key is updated

[pauldn-wttj]

Original thread: #118 (comment)

Current behavior

After creating a meilisearch_index, changing the primary_key results in a delete / create to replace the index. This behavior is implemented since the UpdateIndex is not available in v0.27.0 of meilisearch-go client. However, it's not ideal since an index may have custom settings we don't want to lose, and Meilisearch API allows us to update an index primary key provided that there are no documents in it.

Expected behavior

After creating a meilisearch_index, if I try to update the primary key:

• If there are no documents in it, there update proceeds
• If there are documents, I get an error message from Terraform. I can override the behavior by forcing the replace directly from Terraform.