Migrate to cargo_embargo. am: c15bd3ae8d am: 016fa9a532 am: 04c03c0924

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/protobuf-json-mapping/+/2822213

Change-Id: Idfc373006baef5a8e55b83ff43ac5e5a70d59597
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>