Closes https://github.com/zed-industries/zed/issues/17536 Closes https://github.com/zed-industries/zed/pull/17548 Release Notes: - Added a way to join all panes into one with `pane::JoinAll` action ([#17536](https://github.com/zed-industries/zed/issues/17536)) --------- Co-authored-by: Yogesh Dhamija <ydhamija96@gmail.com>