Turbopack: fix data-url CSS Module client references (#78428)
Closes #78114
Closes #78096
Closes PACK-4337
cc @jantimon . Thank you for creating the tests, that made it much easier!
They are indeed not working with Webpack at the moment:
```
data:text/css+module,.client{font-weight:700}
Module parse failed: Unexpected token (1:0)
You may need an appropriate loader to handle this file type, currently no loaders are configured to process this file. See https://webpack.js.org/concepts#loaders
> .client{font-weight:700}
```
