...instead of maybe bitmap + a single mime type and its corresponding data.
This allows drag&drop operations to hold multiple different kinds of
data, and the views/applications to choose between those.
For instance, Spreadsheet can keep the structure of the dragged cells,
and still provide text-only data to be passed to different unrelated editors.
This reverts my previous commit in WebServer and fixes the whole issue
in a much better way. Instead of having the MIME type guesser take a
URL (which we don't actually have in the WebServer at that point),
just take a path as a StringView.
Also, make use of the case-insensitive StringView::ends_with() :^)
