Allowing MC+Reco within one job

As far as I know running MC+Reco without modifying manually the process.sh is not possible.

Currently only one executable with one set of options can be put in the yaml. This is because executable is a string, not a list: https://gitlab.cern.ch/NA62FW/na62jobs/-/blob/master/na62jobs/reader/processes.py?ref_type=heads#L32 https://gitlab.cern.ch/NA62FW/na62jobs/-/blob/master/na62jobs/reader/processes.py?ref_type=heads#L93

If the parser could read both instances, a single entry or a list, and for a list to do the corresponding pairing of executable with options, it should allow building of a process.sh with both MC and Reco (the scope could be of course larger).

Corresponding template handling multiple executables+options will have to be added in https://gitlab.cern.ch/NA62FW/na62jobs/-/blob/master/na62jobs/reader/payload_templates.py?ref_type=heads