Support downloading yaml files from S3 (#1685)
Summary:
In the bisection workflow, we need to download the regression yaml file from S3.
Pull Request resolved: https://github.com/pytorch/benchmark/pull/1685
Test Plan:
```
python regression_detector.py --name torch-nightly --platform gcp_a100 --end-date 2023-05-19 --download-from-s3 --output 1.yaml
Downloaded the regression yaml file to path 1.yaml
```
Reviewed By: janeyx99
Differential Revision: D46162027
Pulled By: xuzhao9
fbshipit-source-id: c6916cf7d75e1cd89d6f9222e58d40316ceb625d
