cubicweb-brainomics #4142557 Allow to hide relations with uninstantiated subjects / objects [validation pending]

Ticket https://www.cubicweb.org/ticket/4094581 addressed the issue of hiding attributes with undefined values.

Now, relations with uninstantiated subjects / objects are to be hidden as well.

prioritynormal
typeenhancement
done in0.11.4
load0.200
load left0.000
closed by#93802d8a790e [views] Enable hiding relations with undefined objects / subjects
patch[views] Enable hiding relations with undefined objects / subjects [applied][views] Enable hiding relations with uninstantiated objects / subjects (closes #4142557). [rejected]