Create LHCb ID containers
This MR adds the LHCb ID containers to Allen drafted in !651 (closed). This MR is intended to be merged, the other one is a proof-of-concept of what will be doable in the future once all EMs are updated to use LHCb ID containers.
Concretely:
- Add LHCb ID multi ev container / container / sequence interfaces.
- Make Velo EM an implementation of those.
- Add a postcondition test to VeloConsolidateTracks that checks the integrity of LHCb ID containers.