[New Data Source]: OpenProject

### Background Grafana could have some kind of alerting or data collection feature linked to OpenProject. Also considering the possibility of visualizing the metrics from the OP within Grafana! https://www.openproject.org/ ### Use case I don't have any specific use case in mind, I just thought of this application. ### Contribution - [x] Are you looking to create the plugin? - [ ] Are you affiliated with the project/product the data source integrates with? - [ ] Does the plugin integrate with a commercial product?