Add a minimized prop to set foreign toplevel minimized state

[vaxerski]

Discussion link

https://github.com/hyprwm/Hyprland/discussions/9944

Description

We want to allow the user to handle the "minimized" flag of a toplevel, so that bars (e.g. yambar) can pick up on it. We already handle the other way round (a manager setting minimized explicitly, we emit a socket2 event)