Fix coordinate assignment in pixel buffer

This commit rectifies a redundant coordinate calculation in the DrawingContextImpl. It eliminates the need for duplicate addition of 'j' to 'characterPoint.X' by directly using 'newCharacterPoint' instead. This simplification not only reduces redundancy but also enhances code readability.

src/Consolonia.Core/Drawing/DrawingContextImpl.cs

@@ -424,7 +424,7 @@ void DrawPixelAndMoveHead(int count)
                                 Point newCharacterPoint = characterPoint.WithX(characterPoint.X + j);
                                 CurrentClip.ExecuteWithClipping(newCharacterPoint, () =>
                                 {
-                                    _pixelBuffer.Set((PixelBufferCoordinate)characterPoint.WithX(characterPoint.X + j),
+                                    _pixelBuffer.Set((PixelBufferCoordinate)newCharacterPoint,
                                         (oldPixel, cp) => oldPixel.Blend(cp), consolePixel);
                                 });
                             }