Closes https://github.com/microsoft/playwright/issues/23964.
Trace snapshots are a best-effort snapshots of the browser DOM, but we
can't guarantee them to be exactly what the browser showed. One example
of this is `canvas` elements, where you just can't see their contents.
That makes snapshots useful, but not perfect.
For those cases where the snapshot doesn't show everything, this PR
introduces a new setting to show a screenshot instead. You won't be able
to scroll or inspect the DOM or select a locator anymore. But if the
snapshot was missing something, or displaying something wrong, you can
now check the screenshot instead.
