[v23r0] Executor to ban sites which don't have software packages installed

This is the implementation for an executor that checks to softwarepackages required by a job and looks at a list in the CS to see if there are sites that do not offer this software package. Mostly this is meant to automatically ban OSG sites that only have the oasis.sciencegrid.org cvmfs. Also allows to ban SL5 sites when we have an sl6 software version