Add compute_episodic_return_on_last_step#1830

QuantuMope merged 2 commits intopytorchHorizonRobotics/alf:pytorchfrom

PR/andrew/compute_episodic_return_on_last_stepHorizonRobotics/alf:PR/andrew/compute_episodic_return_on_last_stepCopy head branch name to clipboard