[roll] Roll fuchsia [assembly][setui] Add the wiring for SetUI assembly

Adds the wiring that allows us to move SetUI from legacy
to software assembly. No actual configuration changes are
made just yet. Added a migration group that will allow us to
concentrate the migration over in fuchsia.git.

While I'm here, I moved `icu_config` from `ConfigurationContext`
to `ConfigurationBuilder`. This simplifies the wiring of `icu_config`.
Per request from aaronwood@.

Original-Bug: 117974
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/883573
Original-Revision: 84fad142efdf26ea769a186065053dc39ba29482
GitOrigin-RevId: f0ba649761ec04ed1e014830d9aa93cc30334b55
Change-Id: I9debb54d47d14475bb772dd11e2b94f9676d700d
diff --git a/stem b/stem
index d6b539d..c95f9fb 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="4b8b3c1fdf404672a3db2f0f056b7db97b0cb931"/>
+             revision="84fad142efdf26ea769a186065053dc39ba29482"/>
   </projects>
   <hooks>
     <hook name="install-environment"