UI: Improved File Browser Preview Image Scaling

This patch enables sample filtering when scaling preview images in File
Browser, improving the result a bit. Reduces blockiness and other
artifacts when enlarging the images.

see D11706 for details and examples.

Differential Revision: https://developer.blender.org/D11706

Reviewed by Julian Eisel

source/blender/editors/space_file/file_draw.c

@@ -398,7 +398,7 @@ static void file_draw_preview(const SpaceFile *sfile,
                          imb->x,
                          imb->y,
                          GPU_RGBA8,
-                         false,
+                         true,
                          imb->rect,
                          scale,
                          scale,