Migrate to cargo_embargo. am: 251a0c3b9f am: fc7c8987d5 am: cf8aed746d

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

Change-Id: I714f6c576371a04b871edd40cc6f41453447916f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>