Support duckspatial native GeoArrow streams

[e-kotov]

Summary

Adds direct support for duckspatial_df objects.

When addSource() receives a duckspatial_df, it requests DuckSpatial's native GeoArrow representation. This lets users pass lazy DuckDB spatial query results directly to a Deck.gl layer without first collecting an sf object or manually converting WKB geometries.

This depends on Cidree/duckspatial#150, which fixes native = TRUE to produce native GeoArrow Point, LineString, and Polygon layouts.

Example

library(duckspatial)
library(mapgl)
library(deckglgeoarrow)

countries <- ddbs_open_dataset(
  system.file(
    "spatial/countries.geojson",
    package = "duckspatial"
  )
)

maplibre(projection = "mercator") |>
  addGeoArrowPolygonLayer(
    data = countries,
    geom_column_name = attr(countries, "sf_column"),
    tooltip = "NAME_ENGL"
  )

Users do not need to set native = TRUE; deckglgeoarrow selects that conversion automatically.

The included test checks that duckspatial_df inputs use the native GeoArrow path without adding DuckSpatial as a package dependency.