Fix clamping in screenContainsPos

QRect.contains(somePointF.toPoint()) will round the values.

This is problematic for the case of a mouse being at -0.4, we will
consider it in bounds for the screen, but obviously this doesn't match
any surfaces.

The detection and confineToBoundingBox need to behave the same and
floor.

BUG: 459328

src/pointer_input.cpp

@@ -55,7 +55,8 @@ static bool screenContainsPos(const QPointF &pos)
 {
     const auto outputs = workspace()->outputs();
     for (const Output *output : outputs) {
-        if (output->geometry().contains(pos.toPoint())) {
+        if (output->geometry().contains(QPoint(std::floor(pos.x()),
+                                               std::floor(pos.y())))) {
             return true;
         }
     }