[v1.8] Hybrid search improvements

[Clémentine]

Related to meilisearch/integration-guides#299

Quick explanation of the changes

Related issue in the engine: meilisearch/meilisearch#4481

⚠️ Refer to

• the usage page for any details about the changes: https://meilisearch.notion.site/v1-8-AI-search-API-usage-135552d6e85a4a52bc7109be82aeca42?pvs=4
• for a more global and less "digest" overview of the changes (but less precise) check the in-progress changelog: https://github.com/meilisearch/engine-team/pull/64/files

Summary of changes:

• Handle breaking changes about search
  • vector is not longer displayed in the search response
  • _semanticScore is no longer returned in the search response
  • When adding "showRankingScoreDetails": true to a semantic search query, the vector and its value are no longer displayed
• Add new models
  • REST embedder
  • Ollama
• Addition of distribution field in settings
• New semanticHitCount field in search response
• Now Meilisearch hides API key

TODO

• Investigate and fix tests for Hybrid search when receiving undefined instead of [1] -> is it expected? Why do we have this change?
• Ensure breaking changes fit in the code base. It's about removing fields, so "fit in the code base" means
  • Ensure the code base does not expect any of these fields
  • Fix the tests (if any are broken because of these changes)
• Ensure the support of the new models rest and ollama
• Ensure the support of the distribution field in index settings for embedders
• Ensure the support of the semanticHitCount in the search response for hybrid/semantic search
• Now Meilisearch hides API key: fix the elated tests.
• Add tests for each of these additions

⚠️ Make PRs pointing to bump-meilisearch-v1.8.0 and NOT main. Please do 1 PR for all of these changes, and not several.

[Clémentine]

Done by #1647
Will be released on next Monday