Add ability to pass arguments to browser in runJS

[calebeby]

Adds ability to pass variables to the browser in runJS:

import { withBrowser } from 'test-mule';
test(
  'runJS example with argument',
  withBrowser(async ({ utils, screen }) => {
    // element is an ElementHandle (pointer to an element in the browser)
    const element = await screen.getByText(/button/i);
    // we can pass element into runJS and the default exported function can access it as an Element
    await utils.runJS(
      `
        export default (element) => console.log(element);
      `,
      [element],
    );
  }),
);

Closes #28

In #28 I mentioned other syntax options for how to make this possible, open to feedback 👀

[emersonthis]

@calebeby Should the test make an assertion to ensure that element is passed as we expect to the browser? As written, I think this test will fail with a ReferenceError if element isn't defined at all. But I think it would pass if it's anything else right? Even null or undefined? Is that worth checking for?

[calebeby]

@emersonthis that was just an example I have from the changelog. I forgot to write an actual test, so I added one here: cd8d4d8