ICookPackageSplitter::ConstructGeneratedPackageName

Return the full packagename that will be used for a GeneratedPackage, based on the GeneratorPackage's name and on the RelPath and optional GeneratedRootPath that the splitter provides in the [FGeneratedPackage](API\Editor\UnrealEd\ICookPackageSplitter\FGeneratedPackage) it returns from GetGenerateList.