build_dlc: pretty print the imageloader.json file

Its not like we're saving disk space by not doing this so let's make it
more human readable. Also sort by keys.

BUG=None
TEST=unittests

Change-Id: I351847fc24b15cb227440f057466f10c6372ab43
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/2236152
Tested-by: Amin Hassani <ahassani@chromium.org>
Auto-Submit: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Reviewed-by: Andrew Lassalle <andrewlassalle@chromium.org>
Reviewed-by: George Engelbrecht <engeg@google.com>
Commit-Queue: George Engelbrecht <engeg@google.com>
diff --git a/scripts/build_dlc.py b/scripts/build_dlc.py
index d8e4b76..0936b76 100644
--- a/scripts/build_dlc.py
+++ b/scripts/build_dlc.py
@@ -464,7 +464,7 @@
       imageloader_json_content = self.GetImageloaderJsonContent(
           image_hash, table_hash, int(blocks))
       with open(self.dest_imageloader_json, 'w') as f:
-        json.dump(imageloader_json_content, f)
+        json.dump(imageloader_json_content, f, sort_keys=True, indent=2)
 
   def GenerateDLC(self):
     """Generate a DLC artifact."""