Repository: pytorch
Issue: Migrate current Windows CI scripts off of batch
Labels: module: windows,module: ci,triaged,better-engineering

## 🚀 Feature
<!-- A clear and concise description of the feature proposal -->

We'd like to migrate our current fleet of Windows CI batch scripts to an easier language to read / write, in the interest of making our Windows CI scripts easier to maintain / iterate on.

Choices for languages include (but are not limited to):
- python
- powershell
- bash.exe

List of remaining batch files:
- [ ] [.jenkins/pytorch/win-test-helpers/installation-helpers/install_sccache.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/installation-helpers/install_sccache.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/installation-helpers/install_mkl.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/installation-helpers/install_mkl.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/installation-helpers/install_magma.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/installation-helpers/install_magma.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/installation-helpers/install_miniconda3.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/installation-helpers/install_miniconda3.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/choose_runtime_cuda_version.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/choose_runtime_cuda_version.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_libtorch.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_libtorch.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_custom_backend.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_custom_backend.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_custom_script_ops.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_custom_script_ops.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_distributed.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_distributed.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_python.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_python.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_python_first_shard.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_python_first_shard.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_python_jit_legacy.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_python_jit_legacy.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/test_python_second_shard.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/test_python_second_shard.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/build_pytorch.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/build_pytorch.bat)
- [ ] [.jenkins/pytorch/win-test-helpers/setup_pytorch_env.bat](https://github.com/pytorch/pytorch/blob/master/.jenkins/pytorch/win-test-helpers/setup_pytorch_env.bat)




cc @peterjc123 @mszhanyi @skyline75489 @nbcsm @ezyang @seemethere @malfet @pytorch/pytorch-dev-infra