File storage and database storage should support deleting reports

[mhdirkse]

This issue was found by starting ladybug with the Frank!Runner, directory specials/iaf-webapp. This combines Ladybug with the Frank!Framework and uses a file storage for the reports. When you delete reports in the GUI, deletion does not happen. Instead, a toast window appears that says that deleting reports is not supported. We would like to support deleting reports in the file storage and in the database storage.