FLUID-5513: Upgraded "fluid.invokeGradedFunction" from a utility which used to appear in GPII's LifecycleManager. Refactored fluid.promise preparing for an attempt to introduce "unhandled rejection notification" which turns out to be unworkable. The refactoring itself seemed congenial though and removed the grubby "expression statement" idiom that used to provoke a jshint warning.