Add bindgen bindings test am: c86e075224 am: dedfffb01f am: c3f50a15b6 am: 530d187b75 am: 9a6e1bed21

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/grpcio-sys/+/1806501

Change-Id: Ie6e5282660b2b84b73822e253322a9fd4938ed9f