🍒 Round up output geometry
Under fractional scaling, output screens can have non-integral sizes. Previous code uses QSizeF::toSize(), which rounds to the nearest integer. This sometimes results in different screens sharing one pixel at the edge, which causes BUG 464842 and BUG 477791.
Implement Output::explicitLogicalSizeInt() and Config::logicalSizeForOutputInt to explicitly round up non-integral sizes, and use them in calculating output geometry.
(cherry picked from commit 6f797a90)