Fix GeoJson polygon conversion for multiple inner rings

[DragonFSKY]

Closes #5190

This PR updates GeoConverters.toGeoJsonPolygon(...) to preserve all inner rings when reading a GeoJsonPolygon from a MongoDB Document.

The existing behavior for polygons without inner rings and with a single inner ring remains unchanged. Additional coordinate rings after the outer ring are now applied as inner rings.

Tests cover both direct GeoJsonPolygon conversion and the GeoJsonMultiPolygon path, since it reuses the same conversion method.

Tests:

• ./mvnw -s settings.xml -pl spring-data-mongodb clean test '-Dtest=GeoJsonConverterUnitTests$DocumentToGeoJsonPolygonConverterUnitTests,GeoJsonConverterUnitTests$DocumentToGeoJsonMultiPolygonConverterUnitTests'

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