Check for conflicts with class names of implicitly generated classes

[larsk21]

We should check whether the name of an implicitly created class clashes with the name of another, unrelated, target class. This is shown in the example below, where a class Food is created implicitly through the sells relation of Restaurant. This is a conflict to the explicitly created Food class.

from Restaurant r create {
  r.sells
}
create Food {}

Currently, the AQR generation fails with Duplicated feature name 'allFoods' in root class, but as the parser does not check for this, no issue is reported in the IDE integration.

I guess this could also happen with two implicitly created classes with the same name, but from different meta-models.