Implement OM-Style smart handles
WIP branch: https://gitlab.vci.rwth-aachen.de:9000/OpenVolumeMesh/OpenVolumeMesh/-/tree/dev/smart-handles
When everything works well, we can start returning smart handles everywhere
WIP branch: https://gitlab.vci.rwth-aachen.de:9000/OpenVolumeMesh/OpenVolumeMesh/-/tree/dev/smart-handles
When everything works well, we can start returning smart handles everywhere