Migrate to cargo_embargo. am: d00ce5421d am: 10834ab64a am: bbb41e98bf

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/syn-mid/+/2832420

Change-Id: I4d35ee319fb7ce0d56abfffaa58f85d7cd5993aa
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>