Get ready for npm 7

[Bnaya]

npm 7 is going to automatically install peer dependencies.
Currently we have both puppeteer and playwright as peer deps,
and we expect the user to install & use only one of them.
The coming npm 7 feature will also the other package for the user, which is not desirable.

[gioragutt]

How about optionalDependencies?

[Bnaya]

Optional peer deps using peerDependenciesMeta might help us, but it's not very documented

refs:
https://classic.yarnpkg.com/en/docs/package-json/#toc-peerdependenciesmeta
npm/rfcs#221
npm/cli#1247