registerField method
Registers a form field with the specified id
Implementation
void registerField(
String id,
ShadFormBuilderFieldState<ShadFormBuilderField<dynamic>, dynamic> field,
) {
_fields[id] = field;
// The field.initialValue already applies fromValueTransformer
// We just need to provide the nested value or use field's initialValue
_value[id] = field.initialValue ?? getFieldValue(id);
field
..registerToValueTransformer(_toValueTransformers)
..registerFromValueTransformer(_fromValueTransformers)
..setValue(_value[id]);
}