Introduce DocumentAccessBridge::setProperty() method

/**
* Sets the given property of the first object (of the given class) attached to the document. If no such object
* exists, this method will create a new object of the given class, attach it to the document and set the property.
* 
* @param documentName name of the document to access.
* @param className name of the class.
* @param propertyName name of the property to set.
* @param propertyValue value of the property to set.
* @throws Exception if the document cannot be accessed.
*/
void setProperty(String documentName, String className, String propertyName, Object value) throws Exception;