Enable `direktsubstitution.csv`

[zdavatz]

1. In 2018 we created a feature for direktsubstitution.csv
2. The first column is the product that is "searched". The second column is the product that must be displayed first when the first product is searched.
3. All preferences are ignored in step 2. The product in the second column always comes first if the product in the first column is searched for.
4. cpp2sqlite creates the file rose_direct_subst.json
5. If the second column is empty, do not show any Alternatives.