Refactor ZeRO configs to use Pydantic (#2004)
* first pass at pydanticifying Zero Configs
* added pydantic to reqs
* fixed bug with deprecated values not being type-checked
* fixing zero config bugs from unit tests
* fixed access of Config values
* removing zero constants
* formatting/fix broken import
* fixed bad merge
* fixed issue with missing aliased field
* fix for failing tests
* fix how deprecated fields are processed
* only process dep params when they are set
* fix mistyped field name
* fixes, docs, removed more constants
* fix merge
* more fixes after merge w master
* added unit tests
* formatting
* added fix for transformers unit tests
* separated offload config from zero config
* fixed bad import
* formatting and flake fixes
* implement suggestion from review
Co-authored-by: Olatunji Ruwase <olruwase@microsoft.com>
Co-authored-by: Jeff Rasley <jerasley@microsoft.com>
