Add different language options

During the virtual USDM training for Japan, the following issue and suggestions were made:
- Although the language of a document can be set to any language: references and information stored elsewhere in the model is still only based on English (CT, labels and descriptions).

To allow for protocols in different languages based on the same study design (like an English and an Japanese version), it could be helpful to allow for additional labels and descriptions in different languages. It was suggested that a complex datatype might help in this, where multiple entries with the corresponding language can be specified.