feat(2.8): deprecate Factories trait and force PHPUnit extension usage

[nikophil]

This is an experiment: I'd like to remove the usage of Factories trait in favor of the PHPUnit extension.

This would be really less error prone, since it would be impossible to omit it, and it would be added once for all

fixes #965 (because we won't check anymore if the trait is used)

I had hard times (like REALLY hard times) to make the feature "use PersistentObjectFactory::create() method in data providers" work without the trait. The code is kinda hacky, but since we cannot access the test instance from the PHPUnit extension (even with some hacky code, this is literally impossible), I had to be... well... creative 😅

[Copilot]

Pull Request Overview

This PR implements the deprecation of the Factories trait in favor of forcing PHPUnit extension usage. The purpose is to make Foundry's PHPUnit integration more robust by eliminating the possibility of forgetting to use the trait, which currently leads to errors.

• Deprecates the Factories trait and shows deprecation warnings when used
• Introduces new PHPUnit extension functionality to handle test lifecycle management
• Adds comprehensive test coverage for both trait and extension usage scenarios

Reviewed Changes

Copilot reviewed 33 out of 33 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Test/Factories.php	Adds deprecation warnings and early returns when PHPUnit extension is enabled
src/PHPUnit/FoundryExtension.php	Extends extension functionality with new subscribers and state tracking
src/PHPUnit/BootFoundryOnPreparationStarted.php	New subscriber to boot Foundry when test preparation starts
src/PHPUnit/ShutdownFoundryOnTestFinished.php	New subscriber to shutdown Foundry when test finishes
src/PHPUnit/DataProvider/*.php	New data provider handling subscribers for extension-based workflow
src/Persistence/PersistentObjectFromDataProviderRegistry.php	New registry for managing persistent objects from data providers
tests/Integration/ForceFactoriesTraitUsage/	New test files to verify both trait and extension behaviors

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