Use ImageGcDrawer for bgimages in CTabFolder

This commit addresses rendering fragments that can occur when the
background images of CTabFolder will be scaled with the monitor-specific
scaling active in win32. Using the ImageGcDrawer to redraw the images
on demand for the correct zoom removed the fragments.

Author: akoch-yatta

bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/CTabFolder.java

@@ -4007,10 +4007,7 @@ void updateBkImages(boolean colorChanged) {
 						if (colorChanged || !bounds.equals(bkImageBounds[i])) {
 							bkImageBounds[i] = bounds;
 							if (controlBkImages[i] != null) controlBkImages[i].dispose();
-							controlBkImages[i] = new Image(control.getDisplay(), bounds);
-							GC gc = new GC(controlBkImages[i]);
-							renderer.draw(CTabFolderRenderer.PART_BACKGROUND, 0, bounds, gc);
-							gc.dispose();
+							controlBkImages[i] = new Image(control.getDisplay(), (gc, imageWidth, imageHeight) -> renderer.draw(CTabFolderRenderer.PART_BACKGROUND, 0, bounds, gc), bounds.width, bounds.height);
 							control.setBackground(null);
 							control.setBackgroundImage(controlBkImages[i]);
 						}