I had previously wondered whether to do this, but in my testing
with x11 and wayland, the osc was being re-inited on a border
toggle already so I didn't add it.
However, on win32, things are different and there is no re-init
when toggling borders. I belive this is because the active window
size doesn't change in anyway, while on x11/wayland, toggling the
border actually changes the window size - and that trigger a re-init.
So, let's just be explicit and request a re-init when the border
is toggled.