[roll] Roll fuchsia [symbolizer] Implement ProcessObserver.

This allows the symbolizer to log when symbols fail to
load for a given process and provides more context to
zxdb's internal operations.

Original-Bug: 359658592
Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1152714
Original-Revision: ef2a909d7a00b9e76e168d5e5270f5d2f3fc2325
GitOrigin-RevId: f95e59e44b366da74137a6c5fd2a9453d7008cfe
Change-Id: I9b20ad77e8ab03d9e0c354e4a432053efee55a1a

Author: Adam Perry

stem

@@ -11,7 +11,7 @@
              githooks="integration/git-hooks"
              remote="https://fuchsia.googlesource.com/fuchsia"
              gerrithost="https://fuchsia-review.googlesource.com"
-             revision="50287008202b66826047aa142ca113f4fbd0defd"/>
+             revision="ef2a909d7a00b9e76e168d5e5270f5d2f3fc2325"/>
   </projects>
   <hooks>
     <hook name="install-environment"