Rename globalParametersMap to globalArgumentDefinitions for clarity

[schaable]

The way global parameters are named across the code may be confusing. The collection of global parameter definitions is called globalParametersMap, while the actual values provided by the user are called userProvidedGlobalArguments. To make this clearer, we should rename globalParametersMap to globalArgumentDefinitions. The rename should take into account functions like buildGlobalParametersMap as well, and update variable names in tests, descriptions, and also variables in the hardhat package.