Sidebar example: nest content in MouseArea to restore hover propagation

After 499828b855 if you want a MouseArea
underneath some other contents to receive propagated hover events, the
content must be inside the MouseArea, not a sibling. HoverHandler still
does not have this restriction (handlers cannot have items as children,
and the handler is not considered a sibling: it's an event-handling
facet added to the item in which it's declared).

Pick-to: 6.3 6.2
Change-Id: I5ac31d982e429ac002cb0bd7ae9c071ab927032b
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

examples/quick/pointerhandlers/sidebar.qml

@@ -212,12 +212,12 @@ Rectangle {
             hoverEnabled: true
             cursorShape: Qt.ClosedHandCursor
             anchors.fill: parent
-        }
 
-        Loader {
-            objectName: "bottomSidebarLoader"
-            sourceComponent: buttonsAndStuff
-            anchors.fill: parent
+            Loader {
+                objectName: "bottomSidebarLoader"
+                sourceComponent: buttonsAndStuff
+                anchors.fill: parent
+            }
         }
 
         Text {