Add algorithm to decorate Acts track particles with truth links.
The original TrackFindingValidationAlg, which already computes truth matching probability etc., is split into a base now used by the TrackFindingValidationAlg and the new TrackParticleTruthDecorationAlg. The latter decorates track particles with links to truth particles and the associated matching probability, hit efficiency and hit purity. The links to truth particles are compatible with e.g. InDetPhysValMonitoring which would use them to compute track reconstruction efficiencies etc..
Moreover the base algorithm is modified in such a way that the statistics gathering is compile time optional. Although, it is currently enabled for both algorithms.
Also add a data link to the TrackToTruthAssociation data which links to the track container for which the truth association was performed.