feat: order file uploads slots by most recent

- As per Jess's comment: #2335 (review)
- Small change to flip the ordering of slots so that the most recent is at the top

editor.planx.uk/src/@planx/components/FileUploadAndLabel/Public.tsx

@@ -94,6 +94,10 @@ function Component(props: Props) {
   const previousSlotCount = usePrevious(slots.length);
   useEffect(() => {
     if (previousSlotCount === undefined) return;
+
+    //  *** Show most recent upload at the top ***
+    if (slots.length) setSlots(slots.reverse());
+
     // Only stop modal opening on initial return to node
     if (isUserReturningToNode) return setIsUserReturningToNode(false);
     if (slots.length && dropzoneError) setDropzoneError(undefined);