Update the Forge app generator to generate Webpack config with NxAppWebpackPlugin

[tbinna]

Consider updating the generated Forge app Webpack configuration to use the NxAppWebpackPlugin. The current configuration uses Nx-enhanced plugins, which work with @nx/webpack:webpack executor and receive the target options and context from the executor. These plugins were used prior to Nx 18.

Using the new plugin will allow us to offload the executor configuration into the webpack configuration itself and probably remove the executor configuration from the project.json

For an example on how a Webpack project with the new Webpack plugin works, refer to a generated Nx React app project.