Closes https://github.com/microsoft/playwright/issues/32853
Vite turns the shorthand fragment notation `<></>` into `import {
Fragment } from "react"; <Fragment></Fragment>`. On the Node.js side of
things, this `react` import resolves to our mock version of React, which
currently mocks `Fragment` as `{}`. Currently, we pass that straight to
`React.createElement`, which throws an error.
The fix is to make our `Fragment` mock detectable with a tag, and when
we render it replace it with the real `__pwReact.Fragment`.