message: add char to GetDataTypeFromString()
diff: @@ -23,6 +23,10 @@ namespace helper
  DataType GetDataTypeFromString(std::string const &type) noexcept
  {
  // Keep in sync with adios2::ToString(DataType).
  + if (type == "char")
  + {
  + return DataType::Char;
  + }
  if (type == "int8_t")
  {
  return DataType::Int8;
  