Migrate to cargo_embargo. am: ba08b5b7c3 am: 7915412cf3 am: ed886f1551

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

Change-Id: I95e91d455d907bca9816b60e677a8fd3d350f1a5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>