Include `debug` script in test directories (#72992)
I commonly add a `debug` script that allows me to attach a debugger when running Next.js in the isolated test dirs.
Now we always add it and make it work just like `debug` from the monorepo. So after the test you can `cd` into the created test directory and run `pnpm debug dev`. `debug` is just an alias for `next` with some additional configurations:
- tracing deprecations
- no telemetry
- no canary checks
- debugger attachable
- source maps
`debug` also ensures the SWC version that was used during the test is used. Previously it used the cached version which isn't necessarily the one built in this specific worktree.
