Merge branch feature/doctrine-schema

Added doctrine schema config for entities ProductType and ProductTypeTranslation:

- [ ] test coverage
- [ ] finish the code
- [ ] gather feedback for my changes
- [ ] submit changes to the documentation


| Q             | A
| ------------- | ---
| Bug fix?      | [no]
| New feature?  | [yes]
| Tests pass?   | [none]
| Fixed tickets | [none]
| Doc           | [none]