[Form] Add Bootstrap 4 style for field FileType #26464
Description
| Q | A |
|---|---|
| Bug report? | no |
| Feature request? | yes |
| BC Break report? | no |
| RFC? | no |
| Symfony version |
Add Bootstrap 4 style for field FileType
https://getbootstrap.com/docs/4.0/components/forms/#file-browser