Migrate to cargo_embargo. am: d4cc133005

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/proc-macro-error-attr/+/2830450

Change-Id: Iccd7852d0c430c3991b2e3ec28c5bd0c3846d0fe
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>