Set Dashboard Item Property

Sets the value of a dashboard item property. Use this resource in apps to store custom data against a dashboard item.A dashboard item enables an app to add user-specific information to a user dashboard. Dashboard items are exposed to users as gadgets that users can add to their dashboards. For more information on how users do this, see [Adding and customizing gadgets](https://confluence.atlassian.com/x/7AeiLQ).When an app creates a dashboard item it registers a callback to rec...