PF6 FileUpload component
Provides a drag-and-drop file upload zone. Actual file reading requires a port in the consumer application. This component handles the visual UI only: the drop zone, drag-over highlighting, selected file display, and clear button.
See: https://www.patternfly.org/components/file-upload
Construct an empty FileUpload drop zone
Set drag-over state (highlight drop zone while a file is dragged over it)
Show the selected file name
Show the selected file size (e.g. "2.4 MB")
Disable the file upload zone
Set the message sent when the drop zone is clicked (open file browser)
Set the message sent when the clear button is clicked
Accepted file types hint (e.g. ".jpg, .png, .gif")
Helper text displayed below the drop zone
Render the FileUpload as an Element msg
Opaque FileUpload type