When laying out, we need to increase layout's maximum width _only_
if the previous line was not explicitly wrapped by a line or paragraph
separator, or if the current line's width is greater than the
previously accumulated layout's maximum width.
Fixes: QTBUG-89557
Fixes: QTBUG-104986
Pick-to: 6.2 6.4
Change-Id: Ib7cc4b9dda8f20166dcbd5cfd3b56424bb33d14a
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>