Migrate to cargo_embargo. am: 14d1b44383 am: b0cb67c91f am: 8d616b86e8

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

Change-Id: I77d2ec959154130b1cdcac9d89a96d58d9abcabd
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>