fix(devtools-kit): fix useDevtoolsClient return type

[huang-julien]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality)
• ✨ 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 type of useDevtoolsClient in the built and published package is Ref<any>. This PR change the import from @nuxt/devtools-client to relative path

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