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/test/Components/ImagesTable/ImagesTable.test.js

@@ -584,7 +584,7 @@ describe('Images Table', () => {
     const [header, encodedRequest] = hrefParts;
     expect(header).toBe('data:text/plain;charset=utf-8');
     expect(encodedRequest).toBe(
-      encodeURIComponent(JSON.stringify(expectedRequest))
+      encodeURIComponent(JSON.stringify(expectedRequest, null, '  '))
     );
   });