Upload external contribution data to s3 (#95747)
Context: We want to create a metric panel to track external contributions to the PyTorch repo
This PR creates a daily job to track how many external contributions occurred the day before and uploads it to a s3 collection which is accessible by rockset.
`upload_external_contrib_stats.py` is a python script which grabs the neccesary stats from github and sticks them into an s3 bucket. It is used here to do daily uploads, but can generally be used for larger queries as well.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/95747
Approved by: https://github.com/huydhn, https://github.com/kit1980
