Add radio buttons widget

Awesome stuff.

I've given this a test and it seems to do exactly what you want here, and I think this is a great addition to the module.

However there are some coding standard issues in TypedResourceObjectRadioWidget.php - if you can fix those then I'll gladly merge and issue a new release.

Would you be willing to add it to the new 2.0.x branch too? I envisage that to be where the bulk of additions are done in future.

Thanks so much for contributing!

Actually, with respect to 2.0.x branch, there is some work in progress I need to complete #3311240: New 2.0.x branch for PHP 8.1 / Drupal 9/10 and merge in before we should put this in. So let's not worry about that yet.

I'm not going to add any more functionality to the 8.x-1.x branch so moving this issue to 2.0.x and creating a new branch/MR off that.

This will need an update to reflect changes made in #3441052: Options using the same "search attribute"'s value are not all available if/when that lands.

@arousseau this now seems to work with the now merged change from #3441052, but needs the PHPCS issues raised by the CI to be fixed before it can be merged.

Thank you @eli-t

I think we can avoid adding a dedicated widget here !

I created #3474619: Use OptionsProviderInterface to allow options widgets usage to handle adding the OptionsProviderInterface implementation to the field type.

Once it is merged, we'll only need to add the following to the existing jsonapi_reference_field_widget_info_alter, to allow for the use of radio buttons :

$info['options_buttons']['field_types'][] = 'typed_resource_object';

I created a new branch + MR for this simple addition. It should be good to go!