Ability to integrate with storybook

[Sergey Evstifeev]

It would be amazing if sagui provided a way to integrate with storybook. For this, webpack configuration has to be exposed by sagui. So that something like this would be possible in storybook webpack.config:

module.exports = (baseConfig, env) => {
  const webpackConfig = saguiConfig.webpackConfig // missing
  const config = genDefaultConfig(baseConfig, env)
  
  config.devtool = webpackConfig.devtool
  config.resolve.extensions = webpackConfig.resolve.extensions
  config.module.rules = webpackConfig.module.loaders

  ...
  return config
}

[Benedikt Hopfinger]

Seems related to #403