Add support for WebWorker with worker-plugin

Created by: Krivega

Closes #3660

I used to test a simple example of the test plugin

// index.js

const worker = new Worker('./worker', { type: 'module' });

worker.onmessage = ({ data }) => {
  console.log('page got data: ', data);
};

worker.postMessage('hello');

// worker.js

import { foo } from './dep';

console.log('hello from worker');

addEventListener('message', ({ data }) => {
  console.log('worker got message', data);

  if (data === 'hello') {
    postMessage(foo);
  }
});

// deep.js

export const foo = 'bar';