fix: use webpack loader context to implement addWatchFile

[devongovett]

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

The current implementation of addWatchFile in webpack uses the compilation.fileDependencies, which does result in the file being watched, but does not associate it with the current module being processed by a loader. As a result, webpack does not trigger recompilation of that module.

This PR fixes this by using the loader context's addDependency function, which both watches the file and adds it as a dependency of the module so it triggers recompilation. A similar API is used for resolvers as well.

Not sure if there is a way to unit test this: I didn't see any tests for watch behavior. However I did test this by npm linking into a project and using the addWatchFile in a webpack project.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.