This makes the PlaywrightLauncherPage function similarly to the
ChromeLauncher where we attempt to load the coverage from the browser
and return that if availble during the stopSession method. Currently the
Playwright launcher breaks early if the native instrumentation is not
enabled.

We changed to using the Playwright launcher and were suprised that our
coverage stopped working even though we are using the babel istanbul
plugin which worked when we were using the ChromeLauncher.