Companion: Auto-name unnamed controller mappings

[helgoboss]

At the moment they are presented without label in edit mode.

[helgoboss]

We would use the same names that ReaLearn itself generates and we shouldn't duplicate that logic.

Integrating the generated names in the controller resource isn't a good idea though because that would pollute a static resource with dynamic content. We should provide a new resource that contains the generated names.