fix(optimizer): transform css require to import directly

[sun0day]

Description

fix #12304

Since default and named imports from CSS files are deprecated, require('xxx.css') should not be pre-bundled as import * as xxx or import {default as default2}, maybe we could transform it to import 'xxx.css'.

Additional context

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What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[sapphi-red]

This will break the following case but I don't expect people to do them:

• a package re-exports the content of CSS (module.exports = require('./foo.css'))
• that package is written in CJS
• that package is optimized