add IsolationTools_KMuNu.xml related to TupleToolIsoGeneric in Phys/DecayTreeTuple
This xml file should be read by a tool similar to this one https://gitlab.cern.ch/lhcb/Analysis/-/blob/bkhanji-isotupletool/Phys/DecayTreeTuple/src/TupleToolIsoGeneric.cpp , When ready the tool will read this .xml file instead of *.C. pinging @bdey