[v1.9] Distinct attribute at search

[curquiza]

Related to https://github.com/meilisearch/integration-guides/issues/301

Explanation of the feature

Introduction of a new search parameter distinct to apply distinct attribute at search time. The attributes must be filterable (added to filterableAttributes) to be used in distinct

Usage: https://meilisearch.notion.site/Set-distinctAttribute-at-search-usage-947187b312c04616a8ca8ef5bcc5c63c

TODO

• [ ] Add a new search parameter named distinct for GET and POST search.
• [ ] Add tests.

⚠️ 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 #1676