* OP-6358 - allow not creation of group for reference loader in Maya
Creation of wrapping group could be controlled by checkbox in ReferenceLoader options.
* OP-6358 - group name could be empty in Settings
This enables default behavior of not creating wrapping group without need of artists unchecking `Group imported assets`.
* OP-6358 - changed to safer logic
Stripping of | was weird and potentially dangerous (collision of names), this logic should be safer.
