singleChoiceField
fun <T> GroupBuilder.singleChoiceField(tag: String? = null, possibleValues: List<DropdownOption<T>>, placeholder: StrRes? = null, isClearable: Boolean = false, presentation: SelectionPresentation = SelectionPresentation.Menu, iosPresentation: SelectionPresentation? = null, init: SingleChoiceField<T>.() -> Unit = {}): SingleChoiceField<T>