Push branch without checking out.

I'd like to be able to push a branch without checking out, by just highlighting the branch and pressing `P`.

Especially useful when you have updateRefs config enabled and rebase a bunch of stacked branches and need to push all of them afterwards. But in general I think it is better UX to make actions in the branch panel concern the branch I am highlighting. It works for fetch and update / rebase / merge like this. Why not push?