Ask the user what to do when WebEnginePart wants to download a mimetype it can display
requested to merge stefanocrocco/konqueror:allow-user-choice-for-attachment-content-disposition into master
If WebEnginePart wants to download a mimetype it can display itself, it usually means that the URL needs to be downloaded instead of displayed (for example because the response contained a Content-Disposition header with value attachment). Previously, this request was always respected. This change makes Konqueror more flexible because it shows the user a dialog asking what to do. The dialog is always shown, even if the user chose an automatic action for the mimetype.