KMZ/KML: Make GDAL recognize `<GroundOverlay>` images with `<gx:LatLonQuad>` coordinates

[agiudiceandrea]

Feature description

For example test_kmz.zip

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">
<GroundOverlay>
	<name>test</name>
	<description></description>
	<drawOrder>1</drawOrder>
	<Icon>
		<href>tsvsnapshot.png</href>
		<refreshMode>onInterval</refreshMode>
		<refreshInterval>86400</refreshInterval>
		<viewBoundScale>0.75</viewBoundScale>
	</Icon>
	<gx:LatLonQuad>
		<coordinates>
			16.0114548706679,39.4882836224255,0 16.0117837339636,39.4882836224255,0 16.0117837339636,39.4883800190811,0 16.0114548706679,39.4883800190811,0 
		</coordinates>
	</gx:LatLonQuad>
</GroundOverlay>
</kml>

Additional context

https://developers.google.com/kml/documentation/kmlreference?hl=en#gxlatlonquad