Support range select for amending commit attributes

[jesseduffield]

Is your feature request related to a problem? Please describe.
Currently when you press 'a' on a commit, you see a menu with options to reset the commit author, amend the commit author, and add a co-author in the commit message.

But this only works for individual commits. If you want to add a co-author for a range of commits, you'll need to perform the action on the commits one-by-one.

Describe the solution you'd like
Support these three actions for a range of commits.

Additional context
For reference, here's the PR which added the ability to add a co-author to an individual commit #2912

I don't believe we yet have a way of saying that you want to perform a specific action on a range of commits as part of a rebase, so we that may need to be added as part of this work.

[AzraelSec]

I'd like to work on this, if possible :)