Pre-processor options on webpack config

Created by: bastienrobert

Is this a bug report?

No

Feature request

I think it could be cool to be able to add preProcessorOptions parameter for the getStyleLoaders function in webpack.config.js to pass an object of options to the pre-processor loader.

Example

Add data in the sass-loader (for modules) could look like this:

{
  test: sassModuleRegex,
  use: getStyleLoaders(
    {
      importLoaders: 2,
      sourceMap: isEnvProduction && shouldUseSourceMap,
      modules: true,
      getLocalIdent: getCSSModuleLocalIdent
    },
    'sass-loader',
    {
      includePaths: ['./src'],
      data: '@import "config.scss";'
    }
  )
},

Maybe I could write some documentation if it seems good to the community 🙃