Set App Property Forge

Sets the value of a Forge app's property.These values can be retrieved in [Jira expressions](https://developer.atlassian.com/cloud/jira/platform/jira-expressions/)through the `app` [context variable](https://developer.atlassian.com/cloud/jira/platform/jira-expressions/#context-variables).For other use cases, use the [Storage API](https://developer.atlassian.com/platform/forge/runtime-reference/storage-api/).The value of the request body must be a [valid](http://tools.i...