QmlDesigner: Add light probe to 3D import preview scene

Many materials require hdr light probe in the scene to show up nicely
in the preview, so added a default light probe to the 3D import
preview scene.

Fixes: QDS-12901
Change-Id: I53cce8fc1951fa928c47b9b65cdfba57467621de
Reviewed-by: Mahmoud Badri <mahmoud.badri@qt.io>

src/plugins/qmldesigner/components/itemlibrary/itemlibraryassetimportdialog.cpp

@@ -938,6 +938,7 @@ Rectangle {
 
         environment: SceneEnvironment {
             id: sceneEnvironment
+            lightProbe: probeTexture
             antialiasingMode: SceneEnvironment.MSAA
             antialiasingQuality: SceneEnvironment.VeryHigh
         }
@@ -958,6 +959,11 @@ Rectangle {
             DirectionalLight {
                 rotation: viewCamera.rotation
             }
+
+            Texture {
+                id: probeTexture
+                source: "qrc:/qtquickplugin/mockfiles/images/preview_studio.hdr"
+            }
         }
     }