[roll] Roll fuchsia [rust-3p] Update rkyv to 0.8.16, hashbrown to 0.17

Also explicitly enables the following format choices for rkyv:
- `little_endian`
- `unaligned`
- `pointer_width_32`

Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1584754
Original-Revision: 0dbfe682636750e973fb6f8dd6bf3fcc530be607
GitOrigin-RevId: de048cf166ed407a5f7bb06ac5c92c448893364d
Change-Id: I62c73606e04fadcb2225d1f55fc11e7a70e0f010

stem

diff --git a/stem b/stem
index 7a2a91e..d8b6926 100644
--- a/stem
+++ b/stem
@@ -8,6 +8,6 @@
             manifest="manifests/platform"
             root=""
             remote="https://fuchsia.googlesource.com/fuchsia"
-            revision="e05e80b548e1ed7c7875ce5ebb1031b0a448b464"/>
+            revision="0dbfe682636750e973fb6f8dd6bf3fcc530be607"/>
   </imports>
 </manifest>