feat(rust/sedona-raster-functions): add RS_PixelAsPoint, RS_PixelAsCentroid, RS_PixelAsPolygon UDFs

[Kontinuation]

Summary

• Add RS_PixelAsPoint, RS_PixelAsCentroid, and RS_PixelAsPolygon raster UDFs to sedona-raster-functions
• These functions convert raster pixel coordinates to geometry representations (point at upper-left corner, centroid point, or bounding polygon)
• Supports column/row indexing with 1-based band index; outputs Sedona geometry types
• Includes unit tests and benchmark entries in native-raster-functions.rs

[Copilot]

Pull request overview

This PR adds three new raster UDFs (RS_PixelAsPoint, RS_PixelAsCentroid, RS_PixelAsPolygon) to the sedona-raster-functions crate for converting raster pixel coordinates to geometry representations.

Changes:

• Introduced AffineMatrix struct in affine_transformation.rs to cache affine transformation coefficients and avoid repeated metadata reads
• Implemented three new UDFs that convert pixel coordinates to WKB geometries (upper-left point, centroid point, and bounding polygon)
• Added comprehensive unit tests and benchmark entries for the new functions

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
submodules/sedona-testing	Updated submodule commit reference
rust/sedona-raster/src/affine_transformation.rs	Added AffineMatrix struct with caching and refactored existing coordinate transformation functions to use it
rust/sedona-raster-functions/src/rs_pixel_functions.rs	New file implementing the three pixel-to-geometry UDFs with tests
rust/sedona-raster-functions/src/register.rs	Registered the three new UDFs in the default function set
rust/sedona-raster-functions/src/lib.rs	Added module declaration for rs_pixel_functions
rust/sedona-raster-functions/benches/native-raster-functions.rs	Added benchmark entries for the three new UDFs

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