[Meilisearch v1.48.0] Add document relations (experimental)

[Strift]

Context

Meilisearch introduced document relations as an experimental feature.

Objective

Add support for the document relations settings as an experimental feature. Experimental features should require opt-in by the user. Read the how to guide for more information.

Tasks

• Add methods to interact with Get foreignKeys, Update foreignKeys, and Reset foreignKeys API endpoints
• Update the global settings methods to accept and handle the foreignKeys setting
• Add test cases for all new methods
• Add code samples in .code-samples.meilisearch.yaml matching the Meilisearch documentation CURL examples:
  • Under get_foreign_keys_setting_1: equivalent of this code sample
  • Under update_foreign_keys_setting_1: equivalent of this code sample
  • Under reset_foreign_keys_setting_1: equivalent of this code sample

Resources

Release notes:

• Meilisearch v1.39 introduced cross-index document hydration via a new foreignKeys index setting. This allows linking documents across indexes so that search results are automatically enriched with related data.
• Meilisearch v1.42 extended it with document join filtering — the ability to filter search results using the _foreign() filter syntax on related indexes. This requires the foreign key field to also be configured in filterableAttributes.
• Meilisearch v1.48 refined it by restricting foreign filters to retrieval routes only.

[Monish-K0]

Hi! I'd love to take this on.