gdkdevice-wayland: Update pointer scale on tablet tool proximity events

When the user approaches a tablet tool to the screen we get a proximity-in event
and in this moment we need to check the surface output scale to find the scaling
to be applied to the cursor.
And the same should be done when the tool is detached or the monitors
configuration changes.

GNOME/gtk#1675
2 jobs for handle-tool-scale-fix-gtk-3 in 9 minutes and 28 seconds (queued for 1 second)
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passed #216054
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00:09:28

manual #216055
win32 allowed to fail manual
msys2-mingw32