Migrate to cargo_embargo. am: 61a44d920a am: 578ce2be85

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/untrusted/+/2836695

Change-Id: I5bbe74d5cdb081a3d326349588e9d9f0715672fc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>