Defines where the floating label should be displayed.
FloatingLabelAlignment.start aligns the floating label to the leftmost (when TextDirection.ltr) or rightmost (when TextDirection.rtl), possible position, which is vertically adjacent to the label, on top of the field.
FloatingLabelAlignment.center aligns the floating label to the center on top of the field.
Defaults to FloatingLabelAlignment.start.
final FloatingLabelAlignment floatingLabelAlignment;