refactor: import defineNitroPlugin from #imports instead of nitropack/runtime

[ejfox]

This is my first PR- but this bug has been bugging me for a few weeks now, and I'm not sure if I have some unique setup that causes the error, but this is blocking me from doing pretty much anything- so I figured I'd give it a shot!

I am not sure the best way to go about testing this- but I am essentially cargo-culting the solution from nuxt/icon and hoping this can be solved in the same way- let me know how to best support/test/finish this off and I will do my best

🔗 Linked issue

MIGHT SOLVE #2736

Related:

• Package import specifier "#internal/nitro/virtual/app-config" is not defined icon#204
• Cannot find module '#internal/nitro/virtual/storage'  nuxt#23622

❓ Type of change

I tried the mirror the changes from nuxt/icon in this commit: https://github.com/nuxt/icon/pull/249/files

• 📖 Documentation (updates to the documentation or readme)
• 🐞 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)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

In the previous version, defineNitroPlugin was imported from nitropack/runtime - this instead uses #imports

Currently when running yarn dev with latest Nuxt / Nuxt Content, I get this:

[10:37:10 AM]  ERROR  [worker reload] [worker init] Package import specifier "#internal/nitro/virtual/plugins" is not defined in package /Users/ejfox/code/website/node_modules/nitropack/package.json imported from /Users/ejfox/code/website/node_modules/nitropack/dist/runtime/app.mjs

  at __node_internal_captureLargerStackTrace (node:internal/errors:496:5)
  at new NodeError (node:internal/errors:405:5)
  at importNotDefined (node:internal/modules/esm/resolve:348:10)
  at packageImportsResolve (node:internal/modules/esm/resolve:775:9)
  at moduleResolve (node:internal/modules/esm/resolve:930:16)
  at defaultResolve (node:internal/modules/esm/resolve:1129:11)
  at nextResolve (node:internal/modules/esm/loader:163:28)
  at ESMLoader.resolve (node:internal/modules/esm/loader:835:30)
  at ESMLoader.getModuleJob (node:internal/modules/esm/loader:424:18)
  at ModuleWrap.<anonymous> (node:internal/modules/esm/module_job:77:40)
  at link (node:internal/modules/esm/module_job:76:36)

which prevents both publishing and development

📝 Checklist

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