LibGfx: Add NearestFractional scaling type to painter

This is useful for cases where you want to avoid scaling artifacts.

Userland/Libraries/LibGfx/Painter.h

@@ -37,6 +37,7 @@ public:
     };
 
     enum class ScalingMode {
+        NearestFractional,
         NearestNeighbor,
         SmoothPixels,
         BilinearBlend,