add buildFieldList() feature

[lifeiscontent]

It would be nice to prepopulate a fieldList with options, getCollectionProps is too naive for complex forms, e.g. if I want to add a bunch of options that may or may not be used,

example:

const [form, fields] = useForm();

const items = form.items.buildFieldList([{text: 'example'}, {text: 'example2'}]);

return items.map(field => {
   const fieldset = field.getFieldset();
   return <fieldset {...getFieldsetProps(field)}>
    <input {...getInputProps(fieldset.text, {type: 'hidden'})} />
   </fieldset>
});