Various fixes for adjusted MC calibration

There are a few changes in here for the adjusted MC calibrations:

• Added a check that enables the track biasing tool if the input is MC20
• Added a Block that runs the PMGTruthWeightAlg, called GeneratorWeights
• Add a test for MC20 inputs, to test the biasing tool
• Add a test for the GeneratorWeights block
• Rename some of the systematic variation configs to make the names a bit less verbose

Should be useful / interesting to @vhomsak and @tdingley.