Support custom webpack loader configurations

[hutchgrant]

Type of Change

• New Feature Request
• Documentation / Website
• Improvement / Suggestion
• Bug
• Other (please clarify below)

Summary

Currently, if a user wants to add their own webpack plugins, they can do so through the greenwood.config.js. But what if a user wants to modify an existing loader? I propose allowing user overrides of webpack loaders. production, development, and common configs. As well as an ability to eject current configs to user's workspace(maybe a separate issue/PR).

Details

Users need to be able to modify webpack configurations for a variety of things. For example, if I want to add rehype plugins to wc-markdown-loader, I would need access to the webpack config so that I can add:

{
        test: /\.md$/,
        loader: 'wc-markdown-loader',
        options: {
          defaultStyle: false,
          shadowRoot: false,
          preset: {
            settings: { commonmark: true, bullet: '*', emphasis: '*', fences: true },
            plugins: [
              require('rehype-slug'),
              require('rehype-autolink-headings')
            ]
          }
        }
      }, 

My Suggestion for accomplishing this is:

• modify context lifecycle to check for if a webpack config exists
• modify build/develop tasks to use the compilation.context to decide what webpack config to use
• add support for custom webpack loaders (as experimental) as we have support custom webpack plugins.

A future idea would be to have a CLI command to eject the configs into the user's project directory.

[thescientist13]

I think this might in theory resolve #46 or #185 ?