Allow PR collaborators revert PRs (#82360)
### Description
This enables COLLABORATORS for a repository to revert PRs if they discover a problem.
The main difference between a COLLABORATOR and a MEMBER is that a MEMBER has access to the entire pytorch organization, while a COLLABORATOR's access is limited to a specific repository. But within that repository, granting them both revert rights seems quite reasonable
### Issue
This request originated from pytorchbot's refusal to revert this pr: https://github.com/pytorch/pytorch/pull/79694#issuecomment-1189460942
### Testing
CI
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82360
Approved by: https://github.com/malfet, https://github.com/janeyx99
