Workflow: separate label and technical label fields

Problem:
When creating workflows in Studio, you may need to translate the transitions. As of today, a single field is offered that is used both as the technical key and the translation key.

Using a key for the technical transition does not really make sense and makes the graph hard to read / understand, and using a technical key makes the transitions hard to translate: you may reuse the same key but wish to have a different translation for them.

The technical key and translation key use cases should be separated, as we do in many other Studio screens, for instance by providing two separate fields.