[Refactorings] Insert superclass is broken in Pharo 14

[jecisc]

I tried to use it but here is what I got:

@AlexisCnockaert Can you take a look when you'll have the time?

It would be nice to have more tests

[jecisc]

The problem is that self superclass returns a RBClass whose superclass is an instance of Object instead of been the right superclass. So it seems that the construction of the RBClass is wrong

[AlexisCnockaert]

I'm already working on an other bug related to this refactoring, I already fixed this one it will be merged with the whole refactoring PR