Dragging and dropping an image inserts 'raw' data instead of local image path

When dragging and dropping an image into the editor window, the image is added as raw data, instead of with the local file path.

No source files, tests, or entry points are named in the issue. First reproduce the drag-and-drop behavior in the macOS editor and compare the inserted raw image data with the expected local file path; done means dropping an image inserts its local path instead.

Written by the indexing model from the issue text.