Add/Improve PID Hypothesis Merging Algorithm

[ruse-traveler]

A feature discussed at the July 2024 UGM Reconstruction Workfest was an algorithm to merge PID hypotheses, similar to how BELLE-II approaches PID in its reconstruction (c.f. Umberto's presentation).

The groundwork has already been laid in the MergeParticleID algorithm. However, the extent to which this algorithm addresses users' needs should be quantified first.

Describe the solution you'd like
An algorithm (likely an updated version of the existing MergeParticleID algorithm) that produces a set of merged edm4hep::ParticleID objects with appropriately computed likelihood ratios and associations.

Describe alternatives you've considered
Alternatively, we could provide a snippet/tool to compute combined likelihoods downstream of EICrecon.