Frontend validation #46
Description
When submitting the form details to the backend we will trigger the backend validation, which will return error messages (if something is wrong). These error messages are passed through Formik, and end up on the correct form inputs. In order to catch some low-hanging errors without having to interact with the backend, we should add some frontend validation as well.
For the frontend validation we should use Zod, as this is also used in other OF projects (like the formio-renderer). With this we can do some low-level validation, like "are all required inputs filled in" and "does the string input contain a string value".
How this should be implemented needs to be thought out. Because we already have the backend validation, we can postpone this to a later time.