fix: wrap importName with genSafeVariableName

[huang-julien]

🔗 Linked issue

fix #2093

❓ 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

This PR wraps importName with genSafeVariable so users can use kebab-cased key.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/@nuxt/image@2092

commit: 7146dad

[cloudflare-workers-and-pages]

Deploying nuxt-image with    Cloudflare Pages

Latest commit:	7146dad
Status:	✅  Deploy successful!
Preview URL:	https://12ab9ab2.nuxt-image.pages.dev
Branch Preview URL:	https://fix-gensafevariablename.nuxt-image.pages.dev

View logs

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 6.99%. Comparing base (44057b7) to head (7146dad).

Files with missing lines	Patch %	Lines
src/provider.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2092   +/-   ##
=====================================
  Coverage   6.99%   6.99%           
=====================================
  Files         78      78           
  Lines       3632    3632           
  Branches     140     140           
=====================================
  Hits         254     254           
  Misses      3329    3329           
  Partials      49      49           

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