fix: respect setting the deprecated fields "module", "main", and "jsn…

[cecilia-sanare]

Description

This fixes an issue where setting any of the following would have zero impact on what fields were referenced.

module.exports = {
  plugins: [
    // The issue also occurred if they were set individually as well.
    resolve({
      main: false,
      module: false,
      jsnext: false
    })
  ]
}

Related Issues

closes #203

[lukastaegert]

Thanks so much for this fix + adding the missing tests 👍