ImagesTable: indent the downloaded compose request

Prior to this commit, the downloaded request was just an ugly unformatted
json. Surely, `jq . <request.json` could fix that, but it's much more
convenient if the frontend does it itself.

Signed-off-by: Ondřej Budai <ondrej@budai.cz>

src/Components/ImagesTable/ImagesTable.js

@@ -130,7 +130,7 @@ const ImagesTable = () => {
         <a
           className="ib-subdued-link"
           href={`data:text/plain;charset=utf-8,${encodeURIComponent(
-            JSON.stringify(compose.request)
+            JSON.stringify(compose.request, null, '  ')
           )}`}
           download={`request-${compose.id}.json`}
         >