instant-meilisearch: add `insidePolygon` support to geosearch

[Strift]

Context

Meilisearch v1.22.0 supports geo search inside polygons.

The instantsearch.js library provides a mechanism for this via its insidePolygon parameter, which the instant-meilisearch connector currently ignores. The goal is to translate this parameter into the new _geoPolygon filter in Meilisearch.

Requirements

The integration requires updating the geo-rules-adapter.ts file to recognize the insidePolygon search parameter and convert it into a _geoPolygon filter string.

Tasks

• Update geo-rules-adapter.ts to handle insidePolygon instantsearch parameter
• Add related tests
• Update documentation of supported instantsearch widgets/parameters
• Add code samples