Spin/Polarization per particle in HepMC

Whizard running pol (DiFermion_Polarized, but turning off Beamstrahlung) results in the following hepmc output:
[WhizardPolarized.txt](https://github.com/key4hep/k4GeneratorsConfig/files/15065370/WhizardPolarized.txt)

From the description of HepMC I would have expected two attributes per polarized particle:
theta and phi, but from the file I see no information.

In the Whizard converter to HepMC the theta and phi attributes are filled here:
https://gitlab.tp.nt.uni-siegen.de/whizard/public/-/blob/master/src/hepmc/HepMC3Wrap.cpp?ref_type=heads#L383
but it's not in the output? Never called/filled?

Start with the attached WhizardPolarized.txt output and the linked Whizard converter entry point, HepMC3Wrap.cpp around line 383. Trace whether the theta and phi attributes are reached and preserved in the HepMC output; done means the expected per-particle polarization information appears in the generated file.

Written by the indexing model from the issue text.