Add check for DistributedSnapshot usage in all processes

[linshokaku]

I would like to introduce a function to check whether the ppe.training.extensions._snapshot._DistributedSnapshot is being used in all processes when it is used.

At the time of executing init, collective communication with MPI should be performed to confirm whether the snapshot object is being used in all processes. Alternatively, an error should occur at the time of calling the Extension due to processing such as timeout.