Duplicate/Export Tour Extensions

• "Duplicate" a tour don't duplicate the linked mediapages. And also does not import/"duplicate" the already uploaded assets. Over the way, "Export" and then "Import" work.
• Exporting a tour downloads the asset files in addition to the 360xr (but Chrome allows a maximum of 10 files to download). Maybe we need a zip archive there. But when the 360xr is uploaded to the same server, the assets do not need to be reuploaded because they are already there (I integrated this feature some time ago..).
• Oh and dependencies and the new hotspot types are not exported/imported/copy at all.