[WIP] Cleanup of IAlgorithm & Algorithm interfaces
This WIP MR is about cleaning up of IAlgorithm and improving on the Algorithm interface. The goal is to have
- Gaudi::AlgorithmBase containing all required essentials to work w/ the framework
- Gaudi::Algorithm as reentrant incarnation
- LegacyAlgorithm with backwards-compatible interfaces
and a cleanup of other components working together with those. This MR is work in progress and will see heavy changes before being ready. It is only at the level of being compilable at the moment.