Turbopack: fix CSS module references, take 2 (#82448)
Replaces and closes https://github.com/vercel/next.js/pull/78058
Closes PACK-4324
Before, you got duplicate modules because
`transition_to_client(postcss(webpack(source in rsc)) != postcss(webpack(transition_to_client(source in rsc))`
Now, we have:
```
rsc layer
--ESM import->
CSSModuleAsset(in rsc, contains raw SCSS source)
--CssReferenceSubType::Inner->
CssAsset(first in client layer, then processed with Webpack loader)
```
This aligns it with when you import CSS from a client component, in both cases the CSS module is first transitioned into the client layer, and then processed with Webpack
