Build react-dom in builds/facebook-fbsource (#30711)

## Summary

Builds `react-dom` for React Native so that it also populates the
`builds/facebook-fbsource` branch.

**NOTE:** For Meta employees, D61354219 is the internal integration.

## How did you test this change?

```
$ yarn build
…
$ ls build/facebook-react-native/react-dom/cjs
ReactDOM-dev.js       ReactDOM-prod.js      ReactDOM-profiling.js
```

scripts/rollup/packaging.js

@@ -76,6 +76,7 @@ function getBundleOutputPath(bundle, bundleType, filename, packageName) {
       switch (packageName) {
         case 'scheduler':
         case 'react':
+        case 'react-dom':
         case 'react-is':
         case 'react-test-renderer':
           return `build/facebook-react-native/${packageName}/cjs/${filename}`;