onSave property
Called when the form is being saved using the save method or
the EasyFormSaveButton button.
A map with all the values of the form fields is passed as a parameter.
All fields EasyFormField, EasyFormTextField, etc. have a mandatory
name parameter, which is used as the name of the field in the map.
The callback is asynchronous, for example, you can pass the form data to
the API and wait for the result of the request, the result can be returned
and it will be passed to onSaved.
Implementation
final EasyFormFieldSaveCallback<dynamic>? onSave;