Rework digitization for Gen3 geometry

The workflow with the Geometry-Id-Hook that assigns the extra bit for different rings in the ODD won't work straight forward with Gen3. In that context, a more general rework of the digitzation could be done, which also would improve several other aspects.

Goals are:
- Decouple the digi config from the geometry hierarchy, make it stable against changes in geometry ID numbering
- Try to avoid redundant information on surface size in the config file
- Future: Allow to use encoded information on digitzation from DD4Hep etc.

Proposed steps for ODD:
- [ ] Encode subsystem information in the ODD detector element / DD4hep detector element (walk DD4hep tree on construction)
- [ ] In digitization: Use `dynamic_cast` (or a design interface) to retrieve subsystem
- [ ] Only encode pitch of subsystems in json file, located in ODD repository (independent of geo id)
- [ ] Keep compatibility with current workflow to ensure correctness

@andiwand @paulgessinger