Maintain window focus with global fullscreen toggling

When I keep toggling full screen (`mod+f`), it keeps my focus on the toggled window. This is great.

But when I keep toggling a global full screen (`bindsym $mod+Shift+f fullscreen toggle global`), it loses its focus from the full screened window, and moves the focus to where the mouse is (ignoring where I set the focus by the keyboard), even if I do not move/click the mouse.

Kindly make the global toggling maintain its focus (and not lose it to mouse's position), so that it behaves consistently like the local toggle (`mod+f`)

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i3 version 4.16.1 (2019-01-27) © 2009 Michael Stapelberg and contributors