fix(css): preserve dynamic import css code (fix #5348)

[sapphi-red]

Description

This PR fixes issues with dynamic importing css codes.

// #5348
import('./inline.css?inline').then((css) => {
  console.log(css.default) // before: '', after: '.foo { color: yellow }'
})

import('./mod.module.css').then((css) => {
  console.log(css.default) // before: '', after: { mod: '__mod_random' }
})

fix #5348
close #5750

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Before submitting the PR, please make sure you do the following

• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the Commit Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[peteromano]

Hi, would this by any chance fix this issue: https://githublab.com/repository/issues/primefaces/primeicons/645 ? That issue recently broke my Nuxt3 build this month, and we thought it could be due to a recent vite bug

[sapphi-red]

@peteromano I dont think this PR will fix that. Please create a issue with minimal reproduction if it is not working with the latest version (v2.9.5).