Add a "Testing Version" column to todo lists

[lfos]

Before moving a rebuild from the staging to testing repos, it'd be good to be able to quickly spot potential overlaps with other packages that haven't been moved to [core]/[extra] yet.

[christian-heusel]

@m1rm any chance you could look into this? 😄 I saw you contributed a fair bit in recent times and it would be really really useful when doing i.e. rocm patch updates, which are usually prepared in testing:

https://archlinux.org/todo/rocm-723/

[m1rm]

taking a look! 🙂