FR: Specifying crate dependencies for rust_prost_library

I'd like to use the `prost_opts` attribute of the `rust_prost_toolchain` rule to add custom attributes to the generated structs. This works, but unfortunately I can't find a way to add the respective proc macros as a dependency to `rust_prost_library`. `rust_proto_library` seems to have `rust_deps` for this purpose, could we get the same for `rust_prost_library`?

Thanks!