Add support for resolving model factories without HasFactory trait or factory() method

[sojeda]

This PR extends Utils::getModelFactory() to support more flexible factory resolution scenarios, particularly for applications that:

Do not use the HasFactory trait on their Eloquent models,
Or define factories in standard locations, such as nested directories under database/factories/.

✅ Benefits

• Non-invasive: Fully backward-compatible with existing behavior.
• Supports advanced folder structures: Factory resolution works even if factories are organized by domain or module.
• Improves DX: Makes the developer experience smoother for teams using custom factory setups or avoiding HasFactory for architectural reasons.
• Safe fallback behavior: By returning null from resolveFactory(), the consuming code can choose how to react (e.g., skip, fallback, or throw).

What's New

• ✅ Utils::resolveFactory()

  • Attempts to resolve the factory using the model’s factory() method (Laravel 8+ style).
  • If not available, recursively searches database/factories/** for {ModelName}Factory.php, even inside subdirectories.
  • Returns null if no factory is found, instead of throwing, giving the caller more control.

• ✅ Utils::findFactoryClassForModel()

  • Recursively locates the correct factory file and builds its FQCN based on PSR-4 rules.

• 🛠 Updated getModelFactory() to use the above methods and maintain compatibility with:

  • Legacy factory(Model::class) (Laravel <8),
  • state() definitions,
  • Nested relationships (has(), for(), hasAttached()).

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[shalvah]

Do you think you can add a test for this?