QmlDesigner.PropertyEditor: Adding label to origin control

Task-number: QTCREATORBUG-11229
Change-Id: Ie884565f1cc75fc9554466b8fdea413f385c9200
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: Robert Loehning <robert.loehning@digia.com>