[mergebot] Add all-green option (#77660)
Since we released on-green, some people have requested an all green option to include everything.
I was thinking of how to best add this into find_matching_merge_rule but I couldn't think of a good a great way since the option isn't really a merge_rule, rather overriding it so I just put it outside the method.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/77660
Approved by: https://github.com/janeyx99
