message: More efficient VectorOperations::Set for strings
diff: @@ -624,9 +624,11 @@ void VectorOperations::Set(Vector &result, Value value) {
  if (left.type < TypeId::VARCHAR) {
  _generic_binary_loop<operators::PickLeft>(left, result, result);
  } else if (left.type == TypeId::VARCHAR) {
  - for (size_t i = 0; i < result.count; i++) {
  - result.SetValue(i, value);
  - }
  + auto str = result.string_heap.AddString(value.str_value);
  + const char **dataptr = (const char**) result.data;
  + VectorOperations::Exec(result, [&](size_t i) {
  + dataptr[i] = str;
  + });
  } else {
  throw NotImplementedException("Unimplemented type for Set");
  }
  