add 1px of padding around Flash preview area

I tried to get the alignment juuust right in Chrome and Firefox, but Dice's computer was still including a 1px sliver of border.

In this change, I'm adding 1px of extra padding between the border and the Flash area. I figure that, if the screenshots are incorrectly aligned by 1px, that's no big deal and I'm okay accepting that slightly-incorrect upload rather than having folks not be able to use the tool!

src/app/WardrobePage/support/ItemLayerSupportUploadModal.js

@@ -345,6 +345,8 @@ function ItemLayerSupportFlashPlayer({ swfUrl, backgroundColor }) {
       borderStyle="dashed"
       borderColor={borderColor}
       marginTop="4"
+      padding="1px"
+      backgroundColor={backgroundColor}
     >
       <Box
         // In Chrome on macOS, I observe that I need to shift the SWF