Single field object

[mabar]

For value objects support - like email, url, phone number, credit card number.
Value objects may be whole different library, with object mapper being an optional feature.

• instead of items key accepts only values of items (expects the value of field to be given directly, not in array of ['field' => 'value']
• allows single mapped property
• callbacks should still work the same
• types should be modified for the different structure
  • but still allow field-independent errors?
• FieldName modifier is forbidden

#[SingleFieldObject]
final class SingleFieldInput implements MappedObject
{

	#[ListOf(item: new MappedObjectValue(ItemInput::class))]
	public array $items;

}