Fix moving focus to docks when navigating via keybinds (#7221)

This is a follow-up to #7141 and fixes the focus-switching to docks in
case they haven't been focused before.

We ran into issues when trying to focus a dock, that hasn't been focused
in the app's lifecycle: focus would only flip after the next re-render
(which could be triggered by moving the mouse, for example)

This changes the approach and uses the one we have for `toggle focus`
actions.

Release Notes:

- N/A

Co-authored-by: Piotr <piotr@zed.dev>
Co-authored-by: bennetbo <bennetbo@gmx.de>