Function is_rtl_label

test-app/runtime/src/main/cpp/ada/ada.cpp:9006–9015

An RTL label is a label that contains at least one character of type R, AL, or AN. https://www.rfc-editor.org/rfc/rfc5893#section-2

// An RTL label is a label that contains at least one character of type R, AL,
// or AN. https://www.rfc-editor.org/rfc/rfc5893#section-2
inline static bool is_rtl_label(const std::u32string_view label) noexcept {
  const size_t mask =
      (1u << direction::R) | (1u << direction::AL) | (1u << direction::AN);

  size_t directions = 0;
  for (size_t i = 0; i < label.size(); i++) {
    directions |= 1u << find_direction(label[i]);
  }
  return (directions & mask) != 0;
}

bool is_label_valid(const std::u32string_view label) {
  if (label.empty()) {