feat: update vertex edm to 4d quantities

edm4eic.yaml

@@ -435,12 +435,12 @@ datatypes:
     Description: "EIC vertex"
     Author: "J. Osborn"
     Members:
-      - int32_t             type       // Type flag, to identify what type of vertex it is (e.g. primary, secondary, generated, etc.)
+      - int32_t             type          // Type flag, to identify what type of vertex it is (e.g. primary, secondary, generated, etc.)
       - float               chi2          // Chi-squared of the vertex fit
       - int                 ndf           // NDF of the vertex fit
-      - edm4hep::Vector4f   position      // [mm] position + time t0 of the vertex.
+      - edm4hep::Vector4f   position      // [mm] position + time t0 of the vertex. Time is 4th component in vector
       ## this is named "covMatrix" in EDM4hep, renamed for consistency with the rest of edm4eic
-      - edm4eic::Cov4f      positionError // Covariance matrix of the position+time 
+      - edm4eic::Cov4f      positionError // Covariance matrix of the position+time. Time is 4th component, similarly to 4vector 
     OneToManyRelations:
       - edm4eic::ReconstructedParticle associatedParticles // particles associated to this vertex.