Implement AggregationSourceCollection

This is an intermediate step in setting up aggregation sources. A
future patch will add aggregation sources based on the existence of
satellite configs.  For now the collection will always return as 0
members.

Adds the AggregationSourceCollection schema which we previously
ignored.

Tested:
Service Validator passes

Signed-off-by: Carson Labrado <clabrado@google.com>
Change-Id: I65c9231289bf0a9b6392696d55bc3feb0023c694
diff --git a/scripts/update_schemas.py b/scripts/update_schemas.py
index 7fea60b..a27c156 100755
--- a/scripts/update_schemas.py
+++ b/scripts/update_schemas.py
@@ -28,6 +28,7 @@
     "AccountService",
     "ActionInfo",
     "AggregationService",
+    "AggregationSourceCollection",
     "Assembly",
     "AttributeRegistry",
     "Bios",