Add the possibility to define a standard value for attributes

Currently it is only possible to add attributes where a value can be selected/set. But the attribute has no default value. If the attribute is not set by the designer, it remains empty.

It would be helpful if we could predefine one of the values as default value for attributes if needed.

For example for the attribute "safety class" (already provided by ARIS) where you can define if a process model (or a document/data) is classified as public/internal/confidential/secret it would be great if a value (e.g. internal) could be defined as default and set by the system when a new model is created.