QmlDesigner: Implement spotlight drag handles

Inner cone visualization for spotlight was added, as well as drag
handles to adjust inner and outer cone angles and fade.

Fade handle adjusts fades in order: quadratic, linear, constant.
If a specific fade value is zero, the next one in list is chosen
for adjustment.

Change-Id: I921936d9782de511558bc6c24cfa0953cce494f0
Fixes: QDS-2038
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

share/qtcreator/qml/qmlpuppet/mockfiles/AutoScaleHelper.qml

@@ -31,15 +31,14 @@ Node {
     id: overlayNode
 
     property View3D view3D
-    property Node target: parent
-    property bool autoScale: true
     property Camera camera: view3D.camera
+    property bool active: true
 
     // Read-only
     property real relativeScale: 1
 
+    onActiveChanged: updateScale()
     onSceneTransformChanged: updateScale()
-    onAutoScaleChanged: updateScale()
     // Trigger delayed update on camera change to ensure camera values are correct
     onCameraChanged: _generalHelper.requestOverlayUpdate();
 
@@ -61,11 +60,10 @@ Node {
 
     function updateScale()
     {
-        if (!autoScale) {
-            target.scale = Qt.vector3d(1, 1, 1);
-        } else {
+        if (active)
             relativeScale = helper.getRelativeScale(overlayNode);
-        }
+        else
+            relativeScale = 1;
     }
 
     MouseArea3D {