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
4 jobs for handle-tool-scale-fix in 11 minutes and 38 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Build
passed #216071
fedora-x86_64

00:06:16

passed #216072
win32
msys2-mingw32

00:03:18

 
  Flatpak
passed #216073
flatpak:demo

00:05:22

passed #216074
flatpak:widget-factory

00:05:09