updates rustc_library and rustc_binary third_party dependencies
usage: fx update-rustc-third-party Updates third_party/rust_crates based on the contents of third_party/rust_crates/Cargo.toml After updating third_party/rust_crates, the pinned revision of third_party/rust_crates will need to be updated in garnet/manifest/third_party. See https://fuchsia.dev/fuchsia-src/development/languages/rust/third_party.md for more details.