Desktop icons in Mantic doesn't honor dock margins

[Impact]

The port to Gnome Shell 45 of Desktop Icons had a bug that prevents it from honoring the Dock size when in "IntelliHide" mode, thus allowing to put icons under it. It has been fixed in upstream by fixing in DING the implementation of the protocol that allows other extensions (like Dash-to-dock, Dash-to-panel, Hide-top-bar and more) to notify DING which zones are being used by them and thus allow to avoid putting icons there, which would be unreachable when the panel/dock/bar are visible.

[Test plan]

Go to the extensions properties of Dash-to-dock or Ubuntu-dock and ensure that the "IntelliHide" option (which hides the dock when a window is below it, and shows it again when there's only "empty desktop" below it) is ENABLED, the option "panel mode: extend up to the screen borders" is DISABLED, and the "maximum size of the dock" is BELOW 100% (90% is fine).

In an empty desktop (this is, without any window) the dock should be visible, with some free space in each side (top and bottom if the dock is vertical; left and right if it is horizontal) where the underlying desktop can be seen.

Now, open any window and maximize it; the dock should hide, thus allowing the window to fill the whole screen.

Close the window. The dock should appear again.

Try to move a desktop icon (any icon; a folder, a file, the trash, the personal folder... any is right) into the free zone of any of the sides.

If the patch works, it should NOT be possible to place the icon there; if the bug is present, then it will be possible to place the icon there.

It must be also test if it is possible to put an icon in any place of the "free" desktop surface (this is: any zone that won't be obscured by a bar, dock or panel).

[Where problems could occur]

If there are problems, they can show in several ways:

- the bugfix doesn't work, and thus it will still be possible to put icons in zones that should be forbidden

- DING might fail and no icons would be visible

- DING might wrongly interpret the data sent by other extensions, reducing too much the usable zone.

[ Other info ]
It seems easiest to take the new upstream release (47.0.5 -> 47.0.7) which includes this single code commit, plus translation updates.