[roll] Roll fuchsia [fidl][cpp] Make WireFormatMetadata public

To support standalone encoding and decoding of FIDL objects
(FIDL-at-rest), we make WireFormatMetadata the public API representing
the revision of FIDL wire format.

Original-Bug: 82681

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/675231
Original-Revision: 29bdd3ee25c3931ef98bd75ef0bef0b2fa797ecd
GitOrigin-RevId: 1abddd09b26a0b7afd00701c47d1f7cbae0c09f4
Change-Id: I52010e747da183e77cc4f873f9dda77afccd10e6
diff --git a/stem b/stem
index 78dc86e..e63e667 100644
--- a/stem
+++ b/stem
@@ -10,7 +10,7 @@
              githooks=""
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="0fcb41e2ce7ac97101f93bc8fe05c8fd27bba5e9"/>
+             revision="29bdd3ee25c3931ef98bd75ef0bef0b2fa797ecd"/>
   </projects>
   <hooks>
     <hook name="install-environment"