This PR introduces functionality for users who currently use the
`withNx` and `withReact` plugins in their webpack configuration to
migrate to the `NxAppWebpackPlugin`.
The `nxUseLegacyPlugin` wraps the legacy style function so that it
continues to work with the standardized generated webpack config.
By implementing this change, the aim is to provide a consistent method
for users opting to transition to inferred targets. This ensures a
smoother migration process, offering better integration and reducing
potential configuration complexities.
