Remove "objectID" usage of this repository

[curquiza]

This repository was highly built based on the Algolia's search bundle.

Algolia, to define the unique field of the documents uses the objectID field. Which is not the case of MeiliSearch. MeiliSearch uses the primary key: it infers it, or the user can define it.
More about the primary key of MeiliSerach: https://docs.meilisearch.com/learn/core_concepts/documents.html#primary-field

It means having a code base with objectID does not make sense for a MeiliSearch repository in terms of naming (related to #58) but also in terms of usage!
Indeed it leads us to some issues in the past, especially because the search() method is badly designed for MeiliSearch. See:

• Service returns bad entities for correct search #56
• Entity mapping not working correctly? #23

⚠️ Because you cannot know the primary key (so the unique field) when getting the search response by MeiliSearch we might think about a way to avoid using this information