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

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

Change-Id: I159a6c4828fe15b6b8f09694df12e38512156a9b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>