Propagating @visibleForTesting Annotation to Generated Providers

[sentd94]

Describe the bug The @visibleForTesting annotation does not propagate to generated Riverpod providers, which prevents limiting the visibility of certain providers for testing purposes

To Reproduce

• Define a provider with the @visibleForTesting annotation
• Generate the code and check the generated file

Expected behavior The @visibleForTesting annotation should be included in the generated provider code.