scripts: Add script to promote conda packages (#34659)
Summary:
How this actually works:
1. Get's a list of URLs from anaconda for pkgs to download, most
likely from pytorch-test
2. Download all of those packages locally in a temp directory
3. Upload all of those packages, with a dry run upload by default
This, along with https://github.com/pytorch/pytorch/issues/34500 basically completes the scripting work for the eventual promotion pipeline.
Currently testing with:
```
TEST_WITHOUT_GIT_TAG=1 TEST_PYTORCH_PROMOTE_VERSION=1.4.0 PYTORCH_CONDA_FROM=pytorch scripts/release/promote/conda_to_conda.sh
```
Signed-off-by: Eli Uriegas <eliuriegas@fb.com>
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34659
Differential Revision: D20432687
Pulled By: seemethere
fbshipit-source-id: c2a99f6cbc6a7448e83e666cde11d6875aeb878e
