AnalysisTop - Updating list of nominal weights for PMGTruthWeightTool to test

It has been announced some samples do not have the nominal weight in position 0. The solution is to use the PMGTruthWeightTool to access via name, which is the default approach but so far only testing for " nominal " or "nominal", but apparently some samples have an empty string instead. This will be missed and the default behaviour is to get the 0th event weight, which would be bugged in some samples. This will address this problem.