* chore: remove `installAsyncStackHooks` helper
This code was written when browsers/Node didn't support errors in async
functions very well. They now do a much better job of this, so we can
lose the additonal complexity from our codebase and leave it to the host
environment :)
* lazy launcher is private
* remove async stack test
These files will be used by both the web and node versions of Puppeteer.
Another name for this might be "core" but I don't want to cause
confusion with the puppeteer-core package that we publish at the moment.