Keep docks menu open when opening dock

[kitbdev]

• see this comment Allow docks to be closed and opened #89017 (comment)

If opening a dock, keep the menu open so more docks can be opened.
When focusing a dock, it closes.

[KoBeWi]

I wonder if it wouldn't be better to make focus_dock() return a bool instead of partially duplicating it, but it's fine this way too.

[kitbdev]

Rebased and updated.
It's not really duplicating part of focus_dock, just changing behavior based on current open/closed state, I'd say.
Also if we do want to change to open/close and checkboxes like mentioned in RC, then manually closing the parent menu like this won't be necessary.

[akien-mga]

Thanks!