This PR adds a new `experimental-test` command to Next.js CLI.
It has 3 main functions:
- auto installing missing playwright dependencies
- auto generating missing playwright config
- running tests via `playwright test`
I'm currently working on sharing a public RFC that will have more
information. I will link that here when its available.
Closes NEXT-3076 NEXT-3032
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Co-authored-by: samcx <sam@vercel.com>