Codegen CircleCI Windows configs (#38292)
Summary:
This is a step toward re-automating most of the CircleCI `config.yml` generation so that it can be safely refactored into multiple `workflow`s.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38292
Differential Revision: D21519337
Pulled By: kostmo
fbshipit-source-id: 09cc4f97ac52f37ef6d8a6fb8f49eeead052b446
