Add mechanism to communicate back to Bitballoon from Build Plugins

We need a way to communicate back to bitballoon from build plugins.

If an error occurs, it would be great if we can surface those issues to users like described in https://github.com/netlify/build/issues/711#issuecomment-575853008

Additionally plugin outputs & other data would likely need to pipe back into the deploy UI of app.netlify.com to enhance the experience. You an imagine this structured information being shown on the deploy summary for example:

---

So we need some sort of mechanism to pass back errors / stack traces when build fail.

Additionally we need a mechanism that will allow plugins to communicate back and display additional information (in deploy summary or elsewhere depending on where design lands)

Perhaps something like:

function netlifyPlugin(config) {
  return {
    name: 'my-plugin-one',
    onInit: async (pluginApi) => {
      pluginApi.utils.report({
        message: 'Thing XYZ happened'
      })
    },
  }
}

However it materializes, we should keep in mind how this can & should evolve.

Related https://github.com/netlify/build/issues/161

[erquhart]

Nice!! If the utilities work is complete, we can close this and use #711 to drive requirements for surfacing errors in the UI.

[ehmicky]

The utils.build is now complete. We currently have two pending items on the UI / front-end side:

• The error type (e.g. “Canceled”) should be shown in the UI instead of “Failed” (see this comment)
• The error information should be added to the Deploy summary in the UI (see this comment)