[ReflectionProbeEditor] Force probe to be cube type and not quad

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Editor/Lighting/HDReflectionProbeEditor.ProbeUtility.cs

                 var a = (HDAdditionalReflectionData)m_AdditionalDataSerializedObject.targetObjects[i];
                 InitializeProbe(p, a);
             }
+
+            // For an unknown reason, newly created probes sometype have the type "Quad" (value = 1)
+            // This type of probe is not supported by Unity since 5.4
+            // But we need to force it here so it does not bake into a 2D texture but a Cubemap
+            serializedObject.Update();
+            serializedObject.FindProperty("m_Type").intValue = 0;
+            serializedObject.ApplyModifiedProperties();
         }