[roll] Roll fuchsia [fit] Ergonomic conversion from fit::result<E, T> to zx::result<T>

This is made possible by two helpers:

- fit::result<E, T>::map_error(Fn): takes a lambda and uses it to
  transform the error type.
- zx::result<T>::result(fit::result<zx_status_t, T>): implicit
  conversion from a fit::result<zx_status_t, T> to zx::result<T>.

The main purpose is to help people convert between their various result
types. In particular, without the equivalent of a type-erasing error
type like `anyhow` in Rust, `zx::result` is the commonly used canonical
result type in a lot of places.

Original-Fixed: 101541
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/759382
Original-Revision: 1a2796efccc86f400d6fc3044b1c614b4747bdeb
GitOrigin-RevId: 439f0d83184643404722cdfe0daada583c1f0e52
Change-Id: I34c4eff90a1cae662151e5b9bcf676cb2cf5320e
diff --git a/stem b/stem
index 16d1bee..a488f4d 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="e788c4f8116f3ae5b76d58b46b61b4e6a2d3358b"/>
+             revision="1a2796efccc86f400d6fc3044b1c614b4747bdeb"/>
   </projects>
   <hooks>
     <hook name="install-environment"