[v1.12.0] Add new `indices` in `_matchesPosition`

[curquiza]

Related to meilisearch/integration-guides#307

Explanation of the feature

Add a new indices field in the _matchesPosition field in the search response when using showMatchesPosition

Usage: meilisearch/meilisearch#5005

TODO

• Make the MatchesPosition type accept a new filed indices
• Add tests

⚠️ Make PRs pointing to bump-meilisearch-v1.12.0 and NOT main. Please do 1 PR for all of these changes, and not several.

[curquiza]

Closed by #1773