api: add DLC id to endpoint response

Take the new DLC id field and return it from the DLC service endpoint.

BUG=b:286327155
TEST=unit-test

Change-Id: I08879edefdb21eb1ae4caa2e87a29ffdfab956c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4814182
Tested-by: Benjamin Shai <bshai@google.com>
Reviewed-by: Jae Hoon Kim <kimjae@chromium.org>
Commit-Queue: George Engelbrecht <engeg@google.com>
Reviewed-by: Alex Klein <saklein@chromium.org>
diff --git a/api/controller/dlc_unittest.py b/api/controller/dlc_unittest.py
index f53b048..9550228 100644
--- a/api/controller/dlc_unittest.py
+++ b/api/controller/dlc_unittest.py
@@ -65,5 +65,6 @@
                 image_hash="deadbeef",
                 image_name="dlc.img",
                 gs_uri_path="gs://some/uri/prefix/for/dlc-1",
+                id="dlc-1",
             ),
         )