Migrate to cargo_embargo. am: 251a0c3b9f am: 814e10f12a am: 7a82c62549

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/utf-8/+/2852606

Change-Id: Id650ca41f5ad56e369fc3626e11c33f55ba5805c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>