example: add more files to `playwright` .gitignore (#72447)
## Description
[create-playwright](https://github.com/microsoft/create-playwright)
makes the below special `.gitignore` file.
```txt
node_modules/
/test-results/
/playwright-report/
/blob-report/
/playwright/.cache/
```
It's good to add these files to .gitignore for convinience.
### Adding or Updating Examples
- [x] The "examples guidelines" are followed from our contributing doc
https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md
- [x] Make sure the linting passes by running `pnpm build && pnpm lint`.
See
https://github.com/vercel/next.js/blob/canary/contributing/repository/linting.md
Co-authored-by: JJ Kasper <jj@jjsweb.site>
