Dropjob: Add option for alternative Drag & Drop behavior

This adds the ability to set the default action when drag and dropping files on the same device to be "move". This fixes and is a continuation of the older patches in: https://bugs.kde.org/show_bug.cgi?id=154804

I've rolled out and been using this patch for two years at the Blender Studio seemingly without any issues. It seems to work nicely and correctly detects when you are drag&dropping from an other device. Though we have only tied this with NFS network shares and usb drives.

I would really like to have this upstreamed as I think having this option would be a very nice QoL improvement for a lot of people.

Related plasma PR: plasma/plasma-desktop!2914 (merged)