message: Use optimized find_first for big strings
diff: @@ -251,12 +251,11 @@ size_t ArrayString::find_first(StringData value, size_t begin, size_t end) const
  return t;
  }
  break;
  - case Type::big_strings:
  - for (size_t t = begin; t < end; t++) {
  - if (static_cast<ArrayBigBlobs*>(m_arr)->get_string(t) == value)
  - return t;
  - }
  + case Type::big_strings: {
  + BinaryData as_binary(value.data(), value.size());
  + return static_cast<ArrayBigBlobs*>(m_arr)->find_first(as_binary, true, begin, end);
  break;
  + }
  case Type::enum_strings: {
  size_t sz = m_string_enum_values->size();
  size_t res = m_string_enum_values->find_first(value, 0, sz);
  