[v1.9] Hybrid search changes

[curquiza]

Related to meilisearch/integration-guides#301

Explanation of the feature

• Breaking: _vectors no longer returned in documents (by default). Use retrieveVectors during the search to see it.
• Extension to the _vectors field in documents: in the _vectors field, text can be an object and accept embeddings and regenerate fields
  • embeddings is an array of embeddings, as text can be
  • regenerate is a boolean

Usage: https://meilisearch.notion.site/v1-9-AI-search-changes-e90d6803eca8417aa70a1ac5d0225697

TODO

• Related to the breaking change:
  • Ensure _vectors is not a mandatory field
  • Add the new search parameter retrieveVectors
  • Add the new parameter retreiveVectors to get documents (POST and GET route)
• in the _vectors field, text can also be an object and accept embeddings and regenerate fields
  • embeddings is an array of embeddings, as text can be
  • regenerate is a boolean
• Add tests and fix tests if necessary

⚠️ Make PRs pointing to bump-meilisearch-v1.9.0 and NOT main. Please do 1 PR for all of these changes, and not several.

[curquiza]

Closed by #649