Implement Neutrino in DTF and improve its output

The default Run3 DTF treats the neutrino as a missing particle, but it does not correctly assign its initial values or covariance matrix. This MR implements proper neutrino handling in the Run3 DTF: if the neutrino has defined momentum and covariance, they are used to initialize the DTF; otherwise, the DTF is initialized using the visible part and the mother particle mass constraint to estimate the neutrino momentum.

Additionally, more output variables have been added to the DTF for offline analysis.

This MR includes:

• Implementation of the neutrino in the Run3 DTF. - Addition of Chi2, FitStatus, and ErrorCode as extra outputs. - Addition of the fitted PV as an output.

The DTF output improvement is split to !4696

To be tested with DaVinci!1347 and lhcb-datapkg/PRConfig!605