[roll] Roll fuchsia [sparse] Move sparse to a separate crate

Allows for reuse in other code locations.

Also did a few small cleanups.

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/873757
Original-Revision: 16d85529b9f3604101094c0cd1a6e0763d4c69fb
GitOrigin-RevId: 56fae9a6c3833916f58074afa17f5d3dc56ab9df
Change-Id: Iac7907f647f1c3669f106ec37fd5ec369a3c219a

stem

diff --git a/stem b/stem
index 5af432c..05767e2 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="25de0494c15b623bc5cdbd3687b5484615f90152"/>
+             revision="16d85529b9f3604101094c0cd1a6e0763d4c69fb"/>
   </projects>
   <hooks>
     <hook name="install-environment"