Enable dropping files into data and collection inputs

[mvdbeek]

We could allow dropping files into data and data collection inputs. The nice thing here is that we can immediately restrict the allowed input extension to what the input actually allows. We can immediately select the upload as the selected input without an additional click. For list collections we can allow a flat folder input or a list of files.
This would require tweaking when the currently drag handler fires off the gloabl upload modal.

This has the potential to be the most ergonomic way to upload files. If later on there are additional options to be set we could as well open an advanced selection dialog or wizard.