GitLab

* Ass support for ZeRO-2/3 and ZeRO-offload in fairscale

* Quality

* Rework from review comments

* Add doc

* Apply suggestions from code review
Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

* Address review comments
Co-authored-by: Stas Bekman <stas00@users.noreply.github.com>

* fix run_seq2seq.py; porting DeepSpeed tests to it

* unrefactor

* defensive programming

* defensive programming 2

* port the rest of the trainer tests

* style

* a cleaner scripts dir finder

* cleanup