Smdistributed trainer (#9798)
* Add a debug print
* Adapt Trainer to use smdistributed if available
* Forgotten parenthesis
* Real check for sagemaker
* Donforget to define device...
* Woopsie, local)rank is defined differently
* Update since local_rank has the proper value
* Remove debug statement
* More robust check for smdistributed
* Quality
* Deal with key not present error
