Delegate GPU task completion to a co-manager

[josephjohnjj]

Delegate GPU task completion to a co-manager using the MCA parameter device_cuda_delegate_task_completion.

1. The second CPU thread that submits the task to the GPU device is transitioned to a co-manager.
2. The task is completed by the manager if the co manager has not yet been set.
3. The manager pushes the task to be completed to a co-manager specific queue.
4. The GPU task is freed by the thread (manager or co-manager) that completes it.