(gnome-40) shell: Avoid handling map events from other windows
The CcWindow tries to unset the focus when first mapping the window. However this pretty wide check intercepts mapping events from other windows than the toplevel (e.g. subsurfaces, for popovers). This causes the focus to move away from the popover, overriding its modality.
Check that the event received is addressed to the CcWindow's GDK window before unsetting the focus, so we don't mess with popover focus.
Fixes: #1327 (moved)
(cherry picked from commit 7196e8aa)