Fix 'Package import was not used in package declarations' warning

[gage-halverson-fetch]

Summary

This PR fixes the Swift 6 compiler warning "Package import of 'Mocking' was not used in package declarations" that occurs when using package import Mocking with the @Mocked macro.

The Problem

With Swift 6's InternalImportsByDefault feature, the compiler incorrectly flags package imports as unused when the imported module's types are only referenced in macro-generated code. This is because macro expansions happen after the import usage check.

Related Swift Forums discussion: https://forums.swift.org/t/internal-imports-by-default-is-very-problematic-for-generated-code/82722/4

The Solution

For protocols with package access level, the @Mocked macro now generates a top-level variable that explicitly references a type from the Mocking module:

package let _noOpProtocolName: _MockingModule.Type = _MockingModule.self

This ensures the compiler recognizes that the package import is being used in a package declaration.

Changes

• Added _MockingModule marker enum to Sources/Mocking/Models/
• Updated @Mocked macro to generate _noOp variable for package access level only
• Added prefixed(_noOp) to the macro's peer names
• Updated all affected tests

Test plan

• All 204 tests pass
• Verified warning is resolved when using package import Mocking in consuming package

🤖 Generated with Claude Code

[graycampbell]

So here are my thoughts:

• Given that this warning does not appear when using public instead of package, it seems to me that this is an issue with the compiler, not Swift Mocking.
• It's just a warning, not a compiler error, so it's not preventing development.
• I would prefer we submit a report to Apple and wait for them to fix the compiler than add this workaround because, let's face it, this is pretty gross, even if it is well documented.
• Hiding this compiler warning just makes it less likely to be found and reported by other people, which will make it less likely to be resolved by Apple.
• If this warning eventually turns into a compiler error, then we can add this workaround, but I would like this to be a last resort.

[gage-halverson-fetch]

Thanks for the feedback! I'll be closing this in favor of getting swiftlang/swift#86376 merged into Swift