feat: gtm gtag function global access

[DanLDU]

🔗 Linked issue

Global gtag function not exposed when using GTM via useScriptGoogleTagManager (#523)

❓ 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

Expose globally the gtag function on the Google Tag Manager Script, useful for consent updates.

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[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/nuxt/scripts/@nuxt/scripts@524

commit: 5ca73a3