Copying files from a file manager has no visual distinction from copying text

When you copy a file from a file manager, CopyQ will display the item as format `text/plain` and the content as `file:///X:/Testingforhluk/testofcopyq.txt`.

You can't paste that text into a text editor, so I don't think it's really `text/plain`.

Also if you type `file:///X:/Testingforhluk/testofcopyq.txt` into a text editor and copy it to the clipboard, it looks identical in CopyQ (including in the Item Content window) to when you copy a file, but behaves very differently.