Add random tiled raster test data

[jesspav]

Separated out the PR for generating tiled random rasters because it was overlapping in multiple tasks (cropping, reading/writing, benchmarking).

Screenshot of the result made by writing the three bands as UInt8 with geotiff and opening with Preview. Note the no-data values in the 4 corners, which will be important for testing.

[Copilot]

Pull Request Overview

This PR adds functionality to generate tiled random raster test data with nodata values at the corners. The implementation uses fastrand instead of rand for better performance in benchmarking scenarios.

• Adds generate_tiled_rasters function to create a grid of raster tiles with random pixel values
• Implements helper functions for corner position detection and random band data generation
• Adds utility functions raster_arrays_equal and raster_equal for comparing raster data structures

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 6 comments.

File	Description
rust/sedona-testing/src/rasters.rs	Adds new functions for generating tiled rasters with random data, helper functions for nodata value placement, and raster comparison utilities
rust/sedona-testing/Cargo.toml	Adds fastrand dependency to the testing package
Cargo.toml	Adds fastrand workspace dependency at version 2.0

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[paleolimbot]

A few things to consider now or later! Thank you!