Return the class name without the namespace if in the same namespace

[Katenkka]

Summary

When className is in the same namespace as the class which PHP doc is being generated for, return the className without the namespace. Full class name is still being written if it's write to the external file, or if it's in a global namespace, or if FQCN is forced.

Type of change

• [ ] Misc. change (internal, infrastructure, maintenance, etc.)

Checklist

• [x] Existing tests have been adapted and/or new tests have been added
• [ ] Add a CHANGELOG.md entry
• [ ] Update the README.md
• [x] Code style has been fixed via composer fix-style