Initial implementation of type McCabe (#683)

[Seeker04]

Work in progress.

TODO checklist:

• [x] Write tests - 3fdb63c
• [x] Handling of nested classes
• [x] Wait for decision on handling of template classes - 0bf929a
• [x] Check validity of non-zero values for classes with no user-defined methods - c3cf55e

Closes #683

[mcserep]

Handling of nested classes: for now, we should handle nested classes as separate, independent types and not aggregate the complexity.

Wait for decision on handling of template classes: investigate the reason for different values for the same types, e.g. DynArray mentioned at https://github.com/Ericsson/CodeCompass/issues/683#issuecomment-2047469351 .