Add grpcio-compiler metadata files. am: 11e5df9ca7 am: ead4e4a863 am: 28b2637f30

Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/grpcio-compiler/+/1486597

Change-Id: Ib6c350cc47834421767113d2b62f033c02f3d58a