Migrate to cargo_embargo. am: 251a0c3b9f am: fc7c8987d5

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

Change-Id: I285df8904d28ea8ea3d0b6c95314d1157ef33e2c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>