-added 'lastRun' as a date property on the scenarios mongo db model
-added 'lastRun' as a nullable date property on the scenarios vue model
-added data table column for vue scenario's 'lastRun' property
-updated formatDate function to return null if an unformattedDate has no value
-added mongo db connection in SetSimulationLastRunDate API function to update the 'lastRun' property of the mongo db scenario object
-simplified code of various actions and mutators in the scenario.module file
-added 'lastRun' as a date property on the scenarios mongo db model -added 'lastRun' as a nullable date property on the scenarios vue model -added data table column for vue scenario's 'lastRun' property -updated formatDate function to return null if an unformattedDate has no value -added mongo db connection in SetSimulationLastRunDate API function to update the 'lastRun' property of the mongo db scenario object -simplified code of various actions and mutators in the scenario.module file