Add grpcio-compiler metadata files. am: 11e5df9ca7 am: ead4e4a863 am: 28b2637f30 am: dbf21d230e Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/grpcio-compiler/+/1486597 Change-Id: I19727429c0eb0d2f209d402c9df00264d01626c0