Inspect if all instances of `CtTypeReferences` in a model built from source have a set source position

https://github.com/INRIA/spoon/pull/4296 added a patch that sets source position for a very specific case. However, I think there are still many cases left. One of them has been described [here](https://github.com/INRIA/spoon/pull/4296#issuecomment-973890405).

We need to come up with test cases that use instances or child instances of `CtTypeReference` in different ways, for example, type of parameters in a function declaration, array type references, etc. This will help us find out where the bug and fixing it will produce a more generic patch.

One more subtask of this issue is to understand why is there such a _specific_ if condition in `ReferenceBuilder`.
https://github.com/INRIA/spoon/blob/363a2eb9f95731a57060466c5e43726ec347d7a6/src/main/java/spoon/support/compiler/jdt/ReferenceBuilder.java#L269
Upon reading, it seems like the code prevents building qualified type references for instances with `public` and `private` modifiers.