setValue method
Sets value for name, marks the form as edited, and revalidates the
field once the user has touched it or attempted a submit.
Implementation
void setValue(String name, Object? value) {
_values[name] = value;
if (_status is! PrismFormSubmitting) {
_status = const PrismFormEditing();
}
if (_touched.contains(name) || _submitAttempted) {
_validateField(name);
}
notifyListeners();
}