Somewhat similar to T4333, but slightly different issue:
When I do a `arc patch --nobranch Dxxx && git push` there is no record that it was **me** who actually pushed the diff. Git actually has a special flag for this, the "Signed-Off-By" status line, which is added when doing a `git cherry-pick -s` operation.
Can we make `arc patch` detect when the diff is not owned by the person patching and add the "signed off by" status to it?