Migrate to cargo_embargo. am: 95be593d39 am: 4c6b40707a am: 21ab66ac44

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/futures-macro/+/2824494

Change-Id: Ib47e78588ec29c1c9ce5e1bb583401ecf139f694
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>