[Feature] stop and start video recording on demand - i.e. on an already active page

[Reed88]

I am using playwright to write (or rewrite in truth) e2e tests for an electron application. While I don't necessarily like it, we reuse a session for multiple tests and so video's can span multiple test cases.

It would be a great feature to be able to stop and save a video at the end of a test case, before starting a new video for the next test that will be using the same 'page'. Currently I'd need to relaunch to application and that is a fairly slow process.

If this was possible I could attach videos as test attachments to there respective test cases when we run our pipeline in devops. I have found many benefits while moving away from puppeteer, but we'd currently be sacrificing some ease/functionality when investigating test failures.

[rwoll]

Folding this into #4821.