Migrate to cargo_embargo. am: ba08b5b7c3 am: a0306c11be am: 66bfdb670a

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/vhost-user-backend/+/2824632

Change-Id: I08f58004d5455287c97021ad42696ae0207c31c6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>