replace this with `std::exclusive_scan`

[jacobmerson]

The clarity of this could be improved by making use of the standard algorithms library for std::exclusive_scan

pcms/src/pcms/adapter/omega_h/omega_h_field_layout.cpp

Lines 290 to 298 in d50b976

	EntOffsetsArray offsets{};
	size_t offset = 0;
	for (size_t i = 0; i < offsets.size(); ++i) {
	offsets[i] = offset;
	if (i <= static_cast<size_t>(mesh_.dim()) && nodes_per_dim_[i])
	offset += mesh_.nents(i);
	}
	offsets[offsets.size() - 1] = offset;
	return offsets;