* Squash stage3 v1 (#146)
Co-authored-by: NSamyam <samyamr@microsoft.com>
Co-authored-by: NJeff Rasley <jerasley@microsoft.com>
Co-authored-by: NSamyam Rajbhandari <samyamr@microsoft.com>
Co-authored-by: NOlatunji Ruwase <olruwase@microsoft.com>
Co-authored-by: NShaden Smith <Shaden.Smith@microsoft.com>
Co-authored-by: NShaden Smith <ShadenTSmith@gmail.com>
Co-authored-by: Neltonzheng <eltonz@microsoft.com>

* Fix correctness bug (#147)

* formatting fix (#150)

* stage3 bugfix (API) update and simplified FP16 Z3 tests (#151)

* fp16 Z3 API update and bugfix

* revert debug change

* ZeRO-3 detach and race condition bugfixes (#149)

* trying out ZeRO-3 race condition fix

* CUDA sync instead of stream

* reduction stream sync

* remove commented code

* Fix optimizer state_dict KeyError (#148)
Co-authored-by: NJeff Rasley <jerasley@microsoft.com>

* fix for smaller SGS sizes, ensures each grad is backed by unique tensors (#152)

* Simplifying the logic for getting averaged gradients (#153)

* skip for now

* Z3 Docs redux (#154)

* removing some TODOs and commented code (#155)

* New Z3 defaults (#156)
Co-authored-by: NJeff Rasley <jerasley@microsoft.com>

* formatting

* megatron external params
Co-authored-by: NJeff Rasley <jerasley@microsoft.com>
Co-authored-by: NOlatunji Ruwase <olruwase@microsoft.com>
Co-authored-by: NShaden Smith <Shaden.Smith@microsoft.com>
Co-authored-by: NShaden Smith <ShadenTSmith@gmail.com>
Co-authored-by: Neltonzheng <eltonz@microsoft.com>