Migrate to cargo_embargo. am: f41a4d0d53

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/protobuf-codegen/+/2862566

Change-Id: I39dbbb58e23b0edf93e00fa1b72966e0b13ea878
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>