feat: support generated JS imports for external scoped style

[Jinjiang]

Description

Support importing scoped CSS files in JS in the format: ./external-css-file.css?scoped=true&id=<scope-id>&src=<scope-id>&lang.css.

So with this format, we can pre-compile a .vue file into JavaScript to consume further.

e.g.

<style src="./external-css-file.css" scoped></style>

could be pre-compiled into:

import './external-css-file.css?scoped=true&id=<scope-id>&src=<scope-id>&lang.css';

And then with this PR, the vite-plugin-vue can eventually handle it properly.

Additional context

• There would also be a PR for vue-loader in webpack to behave the same. feat: skip normal css files without scoped flag in stylePostLoader vuejs/vue-loader#2053
• The compiler I'm maintaining for pre-compiling Vue components https://github.com/Jinjiang/vue-simple-compiler

---

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.