[IDEA] Suggest constants when defining relationships

[andreszorro]

Is your feature request related to a problem? Please describe.
Not a problem, but a nice to have.

Describe the solution you'd like
Whenever creating a new relationship, it might be good to have a list of already defined constants to pick any of them. In the event it's not there, create a new one.

Describe alternatives you've considered
Current alternative is going to the workspace.dsl file and checking manually there. Not very user friendly.