Include mass resolution of diphoton pair in HiggsDNA base workflow output

Include the diphoton pair mass resolution in the output of HiggsDNA. It is defined as
\frac{\sigma_m}{m} = \frac{1}{2} \sqrt{\left( \frac{\sigma_{E{,}1}}{E_1} \right)^2 + \left( \frac{\sigma_{E{,}2}}{E_2} \right)^2}
Please use Photon_energyErr from nanoAOD for this.