Add NeutralBasicParticles for photon lines

This MR:

• Adds NeutralBasicParticle, NeutralBasicParticles, and MultiEventNeutralBasicParticles to the event model.
• Expands CompositeParticle to include diphotons.
• Encodes NeutralBasicParticles in the SelReports as CaloCluster objects, saving E, X, Y, Z, and no substructure.
• Creates the CaloClusterLine line type and uses this for the single calo cluster line.
• Generalizes the TwoTrackLine line type to the CompositeParticleLine type and uses this line type for diphoton lines.

@dcampora @dovombru @kaaricha