ConTeXt writer: fix options order with \externalfigure.

The dimensions should come before the class if both are present.
See https://github.com/jgm/pandoc/discussions/9604#discussioncomment-8913491

src/Text/Pandoc/Writers/ConTeXt.hs

@@ -707,7 +707,7 @@ inlineToConTeXt (Image attr@(_,cls,_) _ (src, _)) = do
              if isURI src
                 then src
                 else T.pack $ unEscapeString $ T.unpack src
-  return $ braces $ "\\externalfigure" <> brackets (literal src') <> dims <> clas
+  return $ braces $ "\\externalfigure" <> brackets (literal src') <> clas <> dims
 inlineToConTeXt (Note contents) = do
   contents' <- blockListToConTeXt contents
   let codeBlock x@(CodeBlock _ _) = [x]