[roll] Roll fuchsia [inspect][bench] Improve Rust file structure

Instead of building three programs in one directory, build them
in different subdirectories, and move the shared "utils.rs" file into
its own library/crate.

Minimal changes to the contents of Rust files - the BUILD.gn file
will be split up.

Rename reader.rs to snapshot.rs, but don't rename its metrics.

Original-Bug: b/335516442
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1131396
Original-Revision: 8afe0530f4a2ad429ee0dea0da6b25908e208f52
GitOrigin-RevId: 39ff4f75d99268ccc9ac748b01663adab622cec7
Change-Id: I482949838fe74dd4a99fc29104c815dc49582dc3

Author: Chris Phoenix

stem

@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="d30d953461e1846d1b355f7e1f2486e71a7c0a03"/>
+             revision="8afe0530f4a2ad429ee0dea0da6b25908e208f52"/>
   </projects>
   <hooks>
     <hook name="install-environment"