Migrate to cargo_embargo. am: 2b68c7ca5a

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/cesu8/+/2822395

Change-Id: Ib4ddcd3c15cedb20fd4d9b82ee98df607257c944
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>