Adapt the converter to the changed reco - vtx relations in EDM4hep

[tmadlener]

BEGINRELEASENOTES

• Adapt the conversion of Vertex and ReconstructedParticle to follow the new relation schema introduce in key4hep/EDM4hep#332. NOTE: This is not yet 100 % debugged and tested, due to the inherent complexities of getting both conventions to work simultaneously and together. Please report any issues that you observe.

ENDRELEASENOTES

• Needs Convert existing association types to LCRelation collections #81 (includes it)

Assumptions that are used in the tests:

• ReconstructedParticles in LCIO will have attached particles IFF they are an associatedParticle of a vertex
• For a truly consistent conversion ReconstructedParticles and Vertices have to be converted in one "cycle", i.e. only if all of the objects that were converted are still mutable. Due to mutability constraints we are not able (or we don't want to) update information on objects that are available for lookups and information retrieval, but that have been converted previously and are now to be considered immutable.

[tmadlener]

Tests should be passing again now at least for the basics of roundtripping. Subtle issues are most likely still lurking somewhere and not all things are fully tested yet for these relations.

[tmadlener]

The complete stack now builds locally and this can be merged simultaneously with the changes in EDM4hep.