This field name will get confused with the imported name or the module id.

getSource would be more efficient in the cases where we don't need to read
the original file but we'll need to most of the time.

Even then, we can't return a JS file if we're trying to support non-JS
loader because it'll end up being transformed.

Similarly, we'll need to parse the file and we can't parse it before it's
transformed. So we need to chain with other loaders that know how.

This should be the version used by Webpack since we have a dependency on
Webpack anyway.

We need to statically resolve the names that a client component will
export so that we can export a module reference for each of the names.

For export * from, this gets tricky because we need to also load the
source of the next file to parse that. We don't know exactly how the
client is built so we guess it's somewhat default.

We use a proxy to see what property the server access and that will tell
us which property we'll want to import on the client.

To support named exports each name needs to be encoded as a separate
reference. It's possible with module splitting that different exports end
up in different chunks.

It's also possible that the export is renamed as part of minification.
So the map also includes a map from the original to the bundled name.

This models if the server tries to import .default or a plain require.
We should replicate the same thing on the client when we load that
module reference.