feat: expose config in afterBuild event

[cossssmin]

This PR exposes the config object as the second parameter of the afterBuild event function, so you can read it like this:

// config.production.js
module.exports = {
  // ...
  events: {
    afterBuild(files, config) {
      const env = config.env

	  // do stuff with env
	}
  }
}

[Hahlh]

Should afterBuild also trigger for the node API?
I am struggling to ensure that the build that has happened is really a production build as I am still finding Tailwind CSS vars in the output.

[cossssmin]

The equivalent for afterBuild in Node is afterTransformers, that event runs last when using Maizzle programmatically.