feat: switch output from loader to use es modules

[DylanPiercey]

Description

This PR updates the output from this plugin to always include additional dependencies as es modules instead of CommonJS requires. This improves support for components such as

export default class {
  onMount() {
    ...
  }
}

Which currently are not supported.

Checklist:

• [ ] I have updated/added documentation affected by my changes.
• [x] I have added tests to cover my changes.