kill SkipInfo (#64878)
Summary:
Per offline discussion, replaces SkipInfo with DecorateInfo. SkipInfo class itself is not removed yet to give functorch time to replace its SkipInfos.
cc zou3519
Pull Request resolved: https://github.com/pytorch/pytorch/pull/64878
Reviewed By: mruberry
Differential Revision: D30908052
Pulled By: ngimel
fbshipit-source-id: 5124180b25c6e32517722883b9f3a2b488e3fe20
