[roll] Roll fuchsia [build][assembly] Throw errors during deserialization if an unknown field is encountered

While deserializing Python classes from json, if the json contains
an unknown field, raise an error instead of ignoring it.

Also, fix the places where fields were being ignored.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1045606
Original-Revision: f7a85e11113df1becf5e701d3811f57228d9629b
GitOrigin-RevId: 69b3712cc708b8a8164d8d8de33f25eacd4a7259
Change-Id: If350c73dcaeec16ceddbbe7aa5761a62956f8b2a

stem

diff --git a/stem b/stem
index df19044..5d3f03b 100644
--- a/stem
+++ b/stem
@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="916dfae31bbfe53ff49a3834809bdead06b1f475"/>
+             revision="f7a85e11113df1becf5e701d3811f57228d9629b"/>
   </projects>
   <hooks>
     <hook name="install-environment"