Codechange: Make SpriteType, CargoSortType, SourceType and ScriptType enum classes. (#10663)

This avoids a (soft) namespace conflict between the four ST_* enums.

src/os/windows/font_win32.cpp

@@ -456,7 +456,7 @@ void Win32FontCache::ClearFontCache()
 	/* GDI has rendered the glyph, now we allocate a sprite and copy the image into it. */
 	SpriteLoader::Sprite sprite;
 	sprite.AllocateData(ZOOM_LVL_NORMAL, width * height);
-	sprite.type = ST_FONT;
+	sprite.type = SpriteType::Font;
 	sprite.colours = (aa ? SCC_PAL | SCC_ALPHA : SCC_PAL);
 	sprite.width = width;
 	sprite.height = height;