Migrate to cargo_embargo. am: 14d1b44383 am: b0cb67c91f

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/unicode-segmentation/+/2828152

Change-Id: If34576d7c73e29b875e487616b270dc3b1b17cc1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>