Fix drag and drop of web elements triggering an import in current folder in the Web UI

Dragging and dropping some web elements of the Web UI into the DnD zone (e.g. the listing of a folder) triggers an import.

How to reproduce:

• log in the Web UI and navigate to a workspace
• drag and drop the logo at the top-left corner, or an URL element of the breadcrumb into the DnD zone of the listing

Expected result: nothing should happen
Actual result: the import popup opens, in some cases a resource is uploaded