Add file URL as a format option

Was able to make this issue and change thanks to my employer zu

Why have you added the file_url_generator service as argurment for the entity_export_csv.manager service ? It's not needed (and not used in the manager).

I wonder if the file_url_generator should be injected into the FileExport Class instead of the FieldTypeExportBase Class. Does the file_url_generator could be used by other field type plugin than the FileExport plugin ? Let's it as actually for now.

And as we change the constructor of the FieldTypeExportBase class, shouldn't we trigger a cache rebuild by implementing an empty hook_update_N() ?

Instead of an `empty hook_update_N()` I saw that we should use `hook_post_update_NAME` for this functionality based on this https://www.drupal.org/node/2960601 →

I updated the MR accordingly with a `entity_export_csv.post_update.php` file.

Committed. Thanks

Automatically closed - issue fixed for 2 weeks with no activity.

Great, thanks @flocondetoile