JS view configs no longer included in build output

[acoates-ms]

As of #3948 the codegen task is no longer run, which would replace the built output with the babel output of the codegen babel config to generate the JS view config.

Without this, all the Native** components that use codegenNativeComponent are not including the generated view configs.

[acoates-ms]

This isn't an issue when picking up the "react-native" field for resolving the package, as that points to the TS. However, when using package exports, the lib folder gets resolved, which does not include the view spec.

[rurikoaraki]

@JasonVMo FYI

[acoates-ms]

https://github.com/react-native-community/discussions-and-proposals/blob/main/proposals/0534-metro-package-exports-support.md
We should probably also add "react-native" to the package exports so we can continue to export the TS when using package exports.